Preheat your oven to 425°F (220°C) and arrange the diced butternut squash, chopped onion, and garlic cloves on a baking sheet. Drizzle generously with olive oil and sprinkle with salt and freshly cracked pepper. Roast for 30 minutes until the squash is tender and caramelized, then let it cool before blending the mixture with brown sugar and Parmesan cheese until smooth. Chill the filling in the refrigerator for added flavor.

In a food processor, combine all-purpose flour, eggs, and a dash of olive oil. Pulse until the mixture forms a cohesive ball of dough; this should take around 1-2 minutes. Wrap the dough tightly in plastic wrap and let it rest in the refrigerator for 30 minutes.

Dust a clean work surface with flour and roll out the chilled pasta dough to your desired thinness. Using an ice cube tray, fill each cavity with the chilled butternut squash filling. Place another layer of rolled-out dough over the tray, pressing down gently around each filling mound to remove air pockets. Cut individual ravioli with a pastry cutter or knife, ensuring the edges are well-sealed.

Bring a large pot of salted water to a rolling boil and gently add the prepared butternut squash ravioli. Cook them for 2-3 minutes or until they float to the surface. Use a slotted spoon to remove the ravioli from the water, allowing them to drain well.

In a skillet over medium heat, melt unsalted butter until it begins to foam and turn golden brown, about 3-5 minutes. Add fresh sage leaves and cook for another minute until they become crisp and aromatic. Pour in a splash of lemon juice before removing from heat.

Toss the cooked ravioli in the sage brown butter sauce until well-coated. Plate them up with a sprinkling of extra Parmesan cheese and a few more crispy sage leaves on top.