Prep the tin: Heat oven to 375°F (190°C). Lightly coat a 12-cup muffin tin with olive oil spray.
Make the cups: Press a tortilla round (or a wonton wrapper) into each muffin cup.
If using tortillas, you may need to snip small slits around the edges so they mold neatly. Lightly mist the tops with oil.
Par-bake: Bake the shells for 7–8 minutes until lightly crisp but not browned. This keeps them from getting soggy later.
Mix the filling: In a bowl, stir together Greek yogurt, light mayo, ranch seasoning, lemon juice (if using), pepper, and a small pinch of salt.
Fold in chopped chicken, bacon, cheddar, and scallions until evenly coated.
Fill the cups: Spoon the chicken bacon ranch mixture into each shell, mounding slightly. You should get 8–10 cups depending on size.
Bake to set: Return to the oven for 8–10 minutes, until the cups are crisp on the edges and the filling is warmed through. The cheese should be melted.
Finish and serve: Let cool for 5 minutes to set.
Top with extra scallions or a tiny drizzle of ranch if you like. Serve warm or at room temp.