1 (12-ounce) jar roasted red peppers, drained and chopped
1 large egg yolk, beaten
Preheat oven to 400 degrees. In a medium pot over medium heat, combine butter, salt, and 1 cup water. When butter is melted, remove pot from heat, add flour, and whisk well to combine. Return to heat and cook mixture, beating vigorously with a wooden spoon, until dough pulls together and forms a mass, about 3 minutes. Continue to cook, stirring constantly, until dough is no longer tacky, about 2 minutes more. Remove pot from heat and let dough cool slightly. Add eggs one at a time, incorporating completely before adding the next. Stir in cheese and chopped peppers.
Spoon dough into a zip-top bag with the tip cut off and pipe 2-inch rounds onto a sheet pan. With a pastry brush, smooth tops with beaten egg yolk and top with remaining shredded cheese.Bake until risen and browned, about 25 minutes.