Start by boiling the orecchiette in a large pot of salted water. Cook it until it’s al dente, following the package instructions. Before draining, reserve about 1/2 cup of the pasta water—it’s liquid gold for adjusting the sauce later. Set the pasta aside.
In a large skillet over medium heat, cook the chopped bacon until it’s golden and crispy. Use a slotted spoon to transfer the bacon to a paper towel-lined plate, leaving about 2 teaspoons of bacon grease in the skillet. This grease will add incredible flavor to the sauce.
Melt the butter in the skillet with the bacon grease. Add the sliced mushrooms in a single layer and let them cook undisturbed for 3–4 minutes to develop a golden crust. Stir and sauté for another 3 minutes until tender. Toss in the minced garlic and cook for 1 minute, letting its aroma infuse the mushrooms.
In a mixing bowl, whisk the cornstarch with the half-and-half until smooth. Pour this mixture into the skillet, followed by the milk, Parmesan cheese, thyme, salt, and pepper. Stir everything together and let it simmer gently for about 5 minutes. The sauce will thicken and the flavors will meld beautifully.
Add the cooked orecchiette and crispy bacon to the skillet. Use tongs to toss everything together, ensuring the pasta is evenly coated with the luscious sauce. If the sauce feels too thick, stir in a bit of the reserved pasta water. Garnish with extra Parmesan and thyme for a finishing touch.