Crustless Spinach Quiche

Extra-virgin olive oil, for greasing and drizzling

4 ounces smoked gouda cheese, cut into 4 pieces

1 10-ounce package frozen spinach, thawed and squeezed dry

2 large eggs plus 2 egg whites

1 15-ounce container part-skim ricotta cheese

2 tablespoons all-purpose flour

1/2 teaspoon freshly grated nutmeg

6 to 8 scallions, chopped

1 tablespoon grated parmesan cheese

1 teaspoon paprika

2 heads endive, sliced lengthwise

2 tablespoons chopped walnuts