How to Make It
In a small skillet, melt the stick of butter over moderate heat. Add the chopped sage and cook just until fragrant, about 30 seconds; let cool.
In a large saucepan, bring the milk to a simmer. Slowly add the semolina flour in a thin stream, whisking constantly. Cook over moderate heat, stirring with a wooden spoon, until very thick, about 3 minutes. Beat in the eggs and cook over low heat for 2 minutes longer, stirring constantly. Remove from the heat and stir in the salt, sage butter and 1 cup of the Parmesan cheese. Continue stirring until the dough is smooth and glossy. Pour the dough into a 9-by-13-inch baking dish and refrigerate until cool and firm to the touch.
Preheat the oven to 400°. Cut the gnocchi dough into 12 squares, then cut the squares in half on the diagonal to form 24 triangles. Using a spatula, transfer the triangles to a large buttered baking dish. Sprinkle with the remaining 3 tablespoons of cheese and dot with the remaining 1 tablespoon of butter.
Bake for about 25 minutes, or until the gnocchi are golden. Preheat the broiler and broil 8 inches from the heat for 2 minutes, or until golden brown. Let the gnocchi stand for 10 minutes. Sprinkle with pepper and serve.