Preheat oven to 350 degrees Fahrenheit (175 Celsius)
Heat the oil and butter in the skillet over medium/high heat. Add the prepared potatoes cut side down in the skillet. Stir well to coat the potatoes with the butter and oil.
Once coated, arrange the potatoes cut side down in the skillet and cook, without stirring, for at least 7 minutes, or until the potatoes are golden brown.
Add the minced onion, garlic, rosemary, and lemon zest to the potatoes. Stir and cook an additional 5 minutes.
Remove the potatoes from the skillet using a large slotted spoon and set them aside.
Reduce the heat under the skillet to medium and add the flour. Stir well and cook for at least 1 minute. Add the capers, wine, and chicken broth to the skillet and cook, stirring occasionally, until the gravy thickens.
Add the potatoes back into the skillet and stir well to coat the potatoes with the gravy.
Top the potatoes with the Parmesan cheese and carefully place the skillet into the preheated oven for 10 minutes, or until the cheese has melted.
Notes
Store any leftovers in an airtight container in the refrigerator for up to 5 days.May be frozen after cooking in an airtight freezer container for up to 3 months.