I started making Béchamel sauce in my late teens. It was a technique I learnt from one of my sisters who served it to me one evening over ravioli with a red sauce on top. At the time, I had no idea that this creamy, luxurious white sauce was called Béchamel (nor that it was one of the famed French mother sauces). What I did quickly realize back in my university kitchen was that through a simple act of alchemy I was able to transform a pile of goop (melted butter and flour) into a delicious silken sauce through the addition of milk.
When you add milk to a mixture of butter and flour (known as a roux) and bring it to a boil, it transforms into a gloriously smooth and thickened white sauce that looks nothing like its point of origin – you can actually see the butter and flour swelling and the liquid thickening as this happens. The sauce takes on a uniform glossy sheen of the kind that will make you want to skate across its surface and contemplate all that is good in life.
What I find remarkable about using a roux in this recipe is that it doesn’t just thicken the soup (the potato does a fine job of that on its own) it actually transforms the entire texture into a velvety smoothness unmatched by the vegetable alone. I tested this recipe both with and without the roux base and while both had strong taste values, the texture of the roux version was divine. Spoonfuls of silk to the tongue.
In short, if you were thinking of skipping the butter/flour step, you must not.
And speaking of magical transformations, have you tried roasting garlic in the skin lately?
When you roast garlic, it looses the pungent characteristics that so many find off-putting in its raw form, playing down the astringent factor and allowing a mellower & sweeter taste to emerge. The mild caramel notes are completely and utterly crave-worthy (not to mention the roasting process will fill your home with a gorgeous aroma).
And it’s just as easy as Béchamel. The oven does all the work as the garlic cloves are broken down into golden, butter-soft versions of themselves.
Finally, seared mushrooms round off this delightful soup with satisfying morsels of umami deliciousness.
You can sear mushrooms in cast iron for a deep rich color or in a non-stick sauté pan for a bright golden hue. Or, you can do both!
I hope you enjoy this creamy delicious soup infused with roasted garlic and seared mushroom. Be sure to review the Notes section in the recipe card below for best results and options.
- 1 (or 2) heads of garlic
- 1 large yellow onion, peeled and chopped
- 2 pounds (about 4 medium-large) russet potatoes, peeled, roughly chopped and boiled just until fork tender and set aside
- 4 cups vegetable (or chicken) broth
- 4 cups (or so) sliced crimini mushroom (10.5 oz/300 grams), brushed but not rinsed/soaked in water
- ¼ cup salted butter
- ¼ cup flour (see Notes for GF option)
- 1 cup milk
- ¼ cup half and half (10% cream)
- good pinch ground thyme (about ½ tsp) + more fresh sprigs for garnish
- Sea salt & coarse black pepper to taste
- Garnish Suggestions:
- coarse black pepper or paprika
- fresh thyme
- minced green onion/chives
- seared mushroom
- Parmesan or crumbled feta cheese
- Preheat the oven to 375ºF
- With a sharp knife, slice off the top layer of the garlic head/s to expose most of the cloves and peel of as many outer layers of the garlic as possible. You should still be left with a primary layer of skin around the cloves.
- Drizzle the exposed cloves with olive oil and sprinkle with salt and coarse pepper. Wrap the garlic head/s in a piece of aluminum foil and place the foiled bundle/s on a baking sheet.
- Roast in the oven for 40 minutes or so until the garlic is gorgeously fragrant and, once carefully unwrapped, has taken on a golden color and butter soft texture.
- To extract the delicious caramelized garlic from the skin, simply work from the bottom and gently squeeze the garlic through the skin (much like toothpaste) the garlic will ooze out. You must sample (but try not to eat it all!) set the warm roasted garlic aside.
- In a large pot or dutch oven, melt butter over low-medium heat. Add the onions and sauté for 5 minutes or so until translucent. Sprinkle the buttered onions with flour* mixing well to integrate and make sure that the flour doesn't brown/burn while it's mixing. Add the broth, milk, cream, thyme and a few cracks of salt & pepper, whisking to combine. Allow the soup to come to a boil, while continuing to whisk for 10 seconds or so, and then reduce to lowest heat and allow the broth to simmer for another couple minutes as the roux works its magic and the soup begins to thicken. Turn off heat.
- Add the cooked potatoes and roasted garlic cloves.
- Working in batches, carefully transfer ingredients to a blender or food processor and blend until completely smooth. For a more dilute consistency, add a little more broth as desired. Taste the soup and adjust seasonings as desired.
- Meanwhile, in a separate pan, sauté mushrooms in a little bit of butter or olive oil until a nice sear develops. Be sure to allow the pan to heat up first and allow the natural water contained in the mushrooms to be released and eventually burnt off through the cooking process. Set the seared mushrooms aside to cool slightly before adding the majority of them to the blended soup (while retaining a few to garnish the top of the soup).
- Serve the soup warm and topped as desired with fresh thyme sprigs, green onion/chives, black pepper, seared mushroom and/or cheese.
The Flour*: All purpose flour creates a smooth and delectable Béchamel however I did try tapioca starch/flour (a gluten-free substitute) in one version of this soup - it worked perfectly well in terms of thickening the soup although there was a slight difference in terms of smoothness - a very mild graininess that is not detectable in AP flour. I still found it very palatable but if you go with tapioca flour my suggestion would be to whisk it vigorously to create the smoothest texture possible.
Garnish Options - I enjoy this soup topped with some black pepper or paprika, seared mushrooms and fresh thyme for garnish but my boys also love it with cheese. You can play around with this element to suit your tastes.
The Cream - Half and half is what I generally use as my 'heavy cream' - I find it adaptive and perfectly luxuriously but you can sub heavier cream in this portion of the recipe as preferred.
The Mushrooms - Mushrooms are about 90% water by nature so you want to be careful not to rinse or soak mushrooms to avoid ending up with a soggy mess. Instead, use a brush or cloth with a little bit of water to clean. As for type of mushroom, I went with a common mushroom here but you could sub any variety of choice. Oyster mushrooms, for example, have a delicious resilient, somewhat chewy, texture that is irresistible in soup. Depending on where you live and what you have access to, seasonal varieties might also come into play.
Soup Consistency: I find the consistency pretty spot on for our taste but, you can make it more dilute by adding a touch of broth. Alternatively, if the soup is not as thick as you would like, simply add a little tapioca or cornstarch slurry at the very end (in a small bowl, whisk 1 flat tbsp of tapioca flour (or cornstarch) with 1 tbsp of water and then add the slurry to the soup, to thicken somewhat.