Step 1: Brown the Seasoned Chicken - Heat 1 tablespoon of the olive oil with 1 tablespoon of the butter in a large skillet over medium heat. Once the butter has melted and the skillet is hot, add the chicken thighs in a single layer. Sprinkle them evenly with paprika, dried thyme, salt, and black pepper. Let the chicken cook for about 5 to 6 minutes on the first side without moving it around too much. That patience helps you get the golden surface that gives the finished gravy so much character. Flip the thighs and cook another 5 to 6 minutes. They do not need to be completely cooked yet because they will finish in the gravy. Transfer the browned chicken to a plate and keep it nearby.
Step 2: Cook the Onions Until Golden - Add the remaining 1 tablespoon butter and 1 tablespoon olive oil to the same skillet. Do not wipe the pan clean. Those browned bits stuck to the bottom are exactly what you want. Add the sliced onion along with a very small pinch of salt and stir everything together. Cook over medium heat for about 8 to 10 minutes, stirring occasionally. The onions should gradually soften, shrink, and turn golden around the edges. I know it can be tempting to rush this part when somebody is asking how much longer dinner will be, but giving the onions those extra few minutes makes the gravy noticeably richer and sweeter.
Step 3: Add the Garlic - Once the onions are tender and golden, add the minced garlic. Stir constantly for about 30 seconds, just until you can really smell it. Garlic can go from fragrant to scorched quickly, so this is one of those moments when I stay right by the skillet instead of trying to unload the dishwasher at the same time. You are simply waking up the garlic before adding the liquid.
Step 4: Build the Onion Gravy - Pour the chicken broth into the skillet and begin scraping the bottom gently with a wooden spoon or spatula. All those browned bits from the chicken will loosen and melt into the broth, which is a big part of what gives this simple gravy its savory depth. In a small bowl, whisk the cornstarch with the cold water until there are no visible lumps. While stirring the broth, slowly pour in the cornstarch mixture. Keep stirring for 1 to 2 minutes as the sauce begins to thicken. At this point it should lightly coat your spoon but still look loose enough to simmer around the chicken.
Step 5: Simmer the Chicken in the Gravy - Return the browned chicken thighs to the skillet and nestle them down between the onions so each piece gets surrounded by gravy. Spoon a little sauce over the top, cover the skillet, and reduce the heat to medium low. Let everything gently simmer for about 15 to 20 minutes, or until the chicken is completely cooked and tender. Chicken should reach an internal temperature of 165°F at the thickest part. As it simmers, the chicken juices mingle with the broth and onions and the gravy becomes richer. If the sauce thickens more than you like, stir in a small splash of broth or water. If it seems thin, remove the lid for the last few minutes and let it gently reduce.
Step 6: Garnish and Bring It to the Table - Remove the skillet from the heat and taste the gravy carefully. Add another small pinch of salt or black pepper if it needs it, keeping in mind that the flavor will seem a little stronger once the gravy is spooned generously over your side dish. Sprinkle chopped fresh parsley across the top. I like serving the entire skillet family style because there is something wonderfully comforting about putting a pan of golden chicken and onion gravy right in the middle of the table. Make sure everybody gets plenty of those soft onions and an extra spoonful of sauce.