Place all the pasta dough ingredients in a food processor and pulse until it looks like coarse crumbs. Then while the processor is going, slowly drizzle in water until the dough comes together.
Place the dough on a well floured surface and knead it a few times until it gets smooth. Wrap in plastic wrap and refrigerate for at least 30 minutes.
When dough is ready, cut into 8 pieces. Each piece will be a layer of ravioli dough. (You'll be able to fit about 3-4 ravioli after its rolled out).
With floured hands, stretch out the dough slightly and flatten it so it looks like a thick disk. Run it through your pasta machine on the largest setting and allow the pasta to pass through twice (or so). Then go to the next smallest setting and do the same thing. I go up to setting 3-4. You want the pasta to not be too sheer but soft enough as well. Continue with the rest of the dough.
Place your pasta sheets on a dry surface sprinkled with semolina. You can also cover it with a damp cloth to keep it from drying out. Set aside to make filling
Now make the filling. In a bowl, mix together pumpkin, ricotta, egg and spices. Whisk together well so it becomes light/fluffy and incorporated.
When ready, lay one sheet of pasta on a dry and floured surface and use a teaspoon to spoon filling, placing them about 1-2 inches apart. Don't put too much filling, a little goes a long way.
Place another sheet of pasta on top, making sure they lay evenly. Use your hands to gently seal the pasta around the filling. Then use a cookie cutter that is larger than your filling and cut out ravioli. Use a fork to crimp the edges. Place ravioli on surface sprinkled with semolina.
When ready, cook ravioli in salted boiling water until they begin to float, about 4 minutes.
Next, make the brown butter sauce. In a non-stick skillet add butter, walnuts and sage. Allow to cook on medium heat until the butter turns a dark brown color. As soon as it darkens, add in your cooked ravioli and toss gently to coat.
Plate the ravioli and sauce and top with fresh grated parmigiana.