Preheat oven to 350ºF. Spray a regular muffin pan with nonstick cooking spray.: Warmth in the oven creates the environment for even baking and a golden finish, and preheating ensures the biscuit cups begin cooking immediately when placed inside. You will notice the oven hum and the air soften as it reaches temperature, which matters because cold batter, dough, or pans can change bake times. A frequent error is not preheating, which results in underbaked biscuit bottoms. If your oven runs hot, use an oven thermometer, and ensure the muffin pan is centered for balanced heat.
In a large skillet, cook lean ground beef over medium-high heat. Drain excess grease. Add ketchup, sugar, yellow mustard, vinegar, Worcestershire sauce, and onions to the skillet. Stir well. Cook over low heat for 10 minutes, or until the sauce has thickened. Season with salt and black pepper.: As the ground beef hits the hot skillet, it releases a robust sizzle and a toasty aroma that signals proper browning, which builds savory flavor. Draining grease helps prevent a heavy mouthfeel and allows the sauce to cling to the meat. When you add the ketchup and seasonings, the skillet will hiss lightly, and the sauce will begin to reduce, concentrating flavors into a glossy, clingy texture. Low heat lets the sugars and acids marry slowly, producing a balanced sweet tang. Watch the pan as it simmers; if it reduces too fast, lower the heat to avoid burning. A common slip is skipping the reduction, which leaves a watery filling that will make the biscuit soggy. Taste and adjust salt and pepper at the end so the seasoning is bright, not flat.
Open a can of refrigerated biscuits. Separate biscuit dough into 10 biscuits. Using a rolling pin, roll each biscuit into a large circle. Firmly press dough in the bottom and up the side of each muffin cup.: When you work the biscuit dough, you will feel its soft, pliable texture and see how it stretches to the pan edges, creating cups that will hold the filling. Rolling gives you control over thickness, so aim for even, thin circles that will bake through rather than stay raw in the center. Pressing firmly ensures a sealed base, preventing leaks during baking. If the dough resists, let it rest briefly to relax the gluten. A typical mistake is leaving the dough too thick, which yields doughy centers; roll gently and evenly for uniform results.
Spoon the meat mixture into the biscuit cups. Top each biscuit with grated cheese.: As you spoon the warm filling, you will notice the scent of the simmered sauce rise, and the cups will begin to feel like little savory nests. Fill them to just below the rim to avoid overflow while baking. The shredded cheddar cheese melts and creates a creamy cap that browns lightly, adding a pleasant contrast in texture. If you overstuff, the filling can bubble over and create sticky edges, so leave a little headroom. For even melting, distribute cheese evenly and avoid clumping excess in one spot.
Bake in a preheated oven for 17 to 20 minutes, until the biscuits are golden brown. Sprinkle with dried parsley.: In the oven, you will see the biscuit edges puff and turn a warm golden color, while the cheese softens and edges brown slightly. The smell will be savory and comforting, with toasted notes from the biscuit crust. Baking time matters because it ensures the biscuit base cooks through while the filling stays juicy. Pull them when they are evenly golden and the centers register hot. A common oversight is removing them too soon, leaving the bottoms underdone. Let them rest briefly after baking so the filling sets, then sprinkle with dried parsley for a visual finish.