Preheat your oven to 375°F. While the oven’s heating up, dice the roma tomato, slice the green onion, and chop the lettuce into small, bite-sized pieces. Set everything aside in little bowls so they’re ready for assembly.

Line a baking sheet with parchment paper (don’t skip this - cheese sticks!). Lay the cheddar slices out in a single layer, making sure they aren’t overlapping. Bake them for about 5 minutes, just until they’re melted and bubbly around the edges.

Let the melted cheese slices sit on the tray for 2–3 minutes, just enough for them to cool slightly but still be flexible. Then, carefully lift each one and press it into the wells of a muffin tin. They’ll form a little cup shape as they cool. Leave them in the tin for 10–15 minutes so they can firm up completely.

While the cheese cups are cooling, brown the ground beef in a skillet over medium heat. Break it up with a spatula as it cooks. Once it’s no longer pink, drain any excess grease. Stir in the taco seasoning along with a tablespoon of water - just enough to coat the meat and help the flavor stick.

Once the cheese cups have cooled and set, gently remove them from the muffin tin and place them on a tray. Fill each one with a spoonful of taco meat, then top with chopped lettuce, tomato, and a small dollop of sour cream.

Sprinkle the tops with sliced green onion for a little extra flavor and color.

Serve right away while the cheese is still nice and crisp.