Preheat oven to 175ºF with a baking sheet lined with a cooling rack in the middle position.

Season pork chops with salt and pepper to taste. Whisk flour, granulated garlic, granulated, onion, cayenne, and a little salt and pepper.

Heat cooking oil in a skillet over medium-high heat until oil shimmers (a pinch of flour will bubble briskly). Dredge pork chops in seasoned flour, shaking off any excess; add to skillet in a single layer and fry, turning once, until golden brown and cooked through, 2 to 4 minutes per side. Transfer chops to the baking sheet in the oven to keep warm.

Strain oil from the skillet through a fine mesh strainer into a heatproof container; reserve the tasty browned bits. Return 4 tablespoons of the oil to the skillet and place over medium heat; sprinkle with 4 tablespoons of the seasoned flour and cook, stirring often, until flour is the color of peanut butter.

While the roux cooks, strain the diced tomatoes into a measuring cup, pressing to extract liquid. Set drained tomatoes aside; measure 1 cup of the drained liquid (add water if necessary). When roux is at desired color, carefully whisk tomato liquid and chicken stock into skillet; cook, stirring, until thickened slightly. If desired, add some (or all) of the reserved drained tomatoes to make a chunky gravy; season to taste with salt and pepper.

Plate pork chops and top with tomato gravy; serve hot with buttermilk biscuits, passing remaining gravy at the table.