Use your hands to break up the cauliflower florets to small bite sizes. For the mushrooms, remove the stems but leave them whole. For extra large ones, slice them in half. Prepare the garlic and shallot in one bowl.
Preheat a large (12-inch) stainless-steel or cast iron skillet over medium-high heat until it’s hot, about 3 minutes. Lower the heat to medium, add 2 tbsp olive oil, cauliflower florets with a pinch of salt and pepper. Toss every 1-2 minutes with a wooden spoon until the florets are crisp with light brown color, about 4-5 minutes. Transfer them out.
Use the same pan, add ¼ cup olive oil, mushrooms with a pinch of salt and pepper. Try to arrange the mushrooms in a single layer, if possible. Toss and saute them every 4-5 minutes until golden brown and the moisture in the pan has almost evaporated, about 12-15 minutes. Use a splatter guard not a lid.
Return the cauliflower to the pan with garlic and shallot, season with another pinch of salt. Saute and toss until the aromatics are softened, about 15 seconds.
Deglaze the skillet with stock and keep sauteing and tossing for 15 seconds. Add 1 tbsp parsley, give it another toss and transfer them to a large serving plate.
Garnish with more parsley and sprinkle parmesan cheese all over, if using. Serve warm.
Pat mushrooms clean with a towel rather than washing to prevent excess moisture release.
Leave mushrooms whole after trimming to get nice big bites.
Cut cauliflower florets to a uniform size for even cooking.
Use a large 12-inch cast iron or stainless steel skillet to allow moisture to evaporate quickly for caramelized mushrooms.
Stir mushrooms infrequently, only every 4-5 minutes, so they brown properly.
Be patient and cook mushrooms until browned and moisture has fully evaporated for the best texture.
Use a splatter guard instead of a lid so moisture can escape.
Don't rush the process - properly caramelized mushrooms are key for maximizing flavor.
Cook thoroughly to avoid a soggy side dish but don't let the mushrooms burn.