Pat chicken pieces dry with paper towels—this ensures proper browning and prevents steaming. In a small bowl, combine minced garlic, rosemary, thyme, lemon juice, 3 tbsp olive oil, salt, pepper, and paprika into a paste. Coat all chicken pieces thoroughly, reserving 1 tbsp of the marinade for later use.

Heat 1 tbsp olive oil in a large Dutch oven or heavy skillet over medium-high heat until shimmering. Working in batches to avoid crowding, sear chicken skin-side down for 4-5 minutes until golden brown. Flip and sear the other side for 3 minutes. Transfer to a plate once browned.

In the same pot, add sliced onions and mushrooms with the reserved 1 tbsp herb marinade. Cook for 3-4 minutes, stirring occasionally, until vegetables soften slightly and release their moisture. This creates an aromatic bed for braising.

Pour chicken broth into the pot, scraping up any browned bits from the bottom—these flavorful bits intensify the gravy. Return all juicy garlic herb chicken pieces to the pot skin-side up, nestling them among the vegetables. Cover and reduce heat to medium-low. Braise for 18-20 minutes until chicken reaches 165°F internal temperature at the thickest part.

Transfer chicken to a serving platter and tent loosely with foil to keep warm. Increase heat to medium-high and simmer the sauce for 4-5 minutes to reduce slightly. Mix cornstarch and water together, then whisk into the simmering sauce to thicken it into a silky coating that clings beautifully to the chicken.

Whisk in 1 tbsp butter to finish the sauce with luxurious richness. Taste and adjust seasoning with salt and pepper as needed. Pour the sauce and vegetables over the chicken. Let it rest for 3 minutes before serving for maximum tenderness and flavor absorption.