In the same pan, heat butter over medium heat.
Add sliced onions and a pinch of salt. Cook, stirring occasionally, until soft and caramelized, about 10 minutes.
Add the garlic and rosemary; cook until fragrant, about 30 seconds.
Add 2 Tbsp. of the remaining flour to the pan. Mix the flour into the onions and cook to dissolve, about 2 minutes.
Pour in the chicken broth, scraping up the browned bits from the bottom of the pan. Let the liquid reduce and thicken slightly, about 2 minutes.
Whisk in the heavy cream and simmer for 1-2 minutes until thick.
Return the pork chops to the pan. Coat them in the sauce and let simmer until the pork is completely cooked through, about 5 minutes.