Spray a 12-cup metal mini muffin tin with the olive oil spray. Press a square of pasta into each cup. Set aside.
Mix together the ricotta, chile paste, salt and oregano in a small bowl. Place a heaping teaspoon of the cheese mixture in the bottom of the pasta shells. Top with 1/2 teaspoon of the marinara. Press a piece of the shrimp gently into the cheese so the ends are sticking out. Spray the bites with the olive oil spray.
Bake until the pasta is brown, the sauce is bubbling and the shrimps are cooked through, about 18 minutes. Remove the bites from the mold to cool slightly. Top with a basil leaf and serve.