Melt the butter and olive oil together in a large pot over medium-high heat. Once it gets all foamy and hot, add your diced onion and cook for about 3 minutes until it starts getting soft. You'll know it's ready when the edges turn slightly golden and it smells amazing (that's how I know I'm doing it right).

Add the minced garlic to the pot and stir constantly for about 30 seconds. This is super quick because garlic burns fast—don't walk away during this part or you'll end up with bitter garlic flavor like I did once. Keep your eye on it and stay close.

Dump in your sliced mushrooms and let them cook for about 8-10 minutes without stirring constantly. This is where the magic happens—they'll release moisture first, then that liquid will evaporate and they'll start to brown. I always stir occasionally after the first few minutes so they don't stick to the bottom.

Sprinkle the flour over the mushrooms and stir everything together until there's no dry flour left. Cook for another minute so the flour gets incorporated and you don't have clumpy texture later. This is a game-changer because it helps thicken the soup naturally.

Pour in the chicken broth slowly while stirring so you don't get any lumps. Add the bay leaf and dried thyme, then bring the whole pot to a gentle boil. Once it starts bubbling, reduce the heat to medium-low and let it simmer for about 15 minutes.

Remove the bay leaf carefully (trust me, you don't want to bite into that later). Stir in the heavy cream and taste the soup—add more salt and pepper if you think it needs it. This creamy mushroom soup should taste rich and savory at this point.

Let everything heat through for another 2-3 minutes on low heat without letting it boil hard. Don't panic if it looks a little thin right now because it'll thicken as it cools slightly. Ladle it into bowls and serve immediately while it's still warm and steamy.