Place the flour on a clean work surface and make a wide well in the center. Crack the eggs into the well. Using a fork, gently whisk the eggs, gradually incorporating flour from the edges until a paste forms. Knead by hand for about 8–10 minutes until the dough is silky and elastic. Wrap in plastic and let it rest at room temperature for 30 minutes.

In a bowl, mix the pumpkin, Parmesan, ricotta, nutmeg, salt, and pepper. If the mixture feels too wet, you can sauté it in a pan for 5 minutes to cook off excess moisture. Let it cool completely.

Divide the dough into 4 pieces. Roll each piece out very thin (using a pasta machine or rolling pin) until you can almost see your hand through it. Place small teaspoons of filling 2 inches apart on one sheet of pasta. Drape a second sheet over the top. Press firmly around the filling to remove air bubbles (this prevents bursting). Cut into squares using a pasta wheel or knife.

In a large skillet, melt the butter over medium heat. Once it foams, add the sage leaves. Continue cooking until the butter turns a medium amber color and smells nutty. Add the lemon juice and remove from heat immediately so it doesn't burn.

Cook the ravioli in a large pot of salted boiling water for 3–4 minutes (they will float when done). Use a slotted spoon to transfer them directly into the brown butter sauce. Gently toss to coat.