Pre-heat your oven to 400 degrees. Line a baking sheet with parchment.
Place the cubed butternut squash on the prepared baking sheet. Drizzle with 1½ tablespoons olive oil, and add the brown sugar, cinnamon, cayenne pepper and a good pinch of salt. Toss to coat. Roast for 20-25 minutes, stirring once halfway through, until the squash is tender and lightly browned. Transfer the squash to a bowl and mash with a fork. (A light mashing will do, friends. Texture is a good thing.)
While your squash is in the oven, fry up some sage leaves. Heat 2 tablespoons of olive oil in a small saucepan over medium-high heat. When the oil is very hot, add the sage leaves in batches and cook for 3-5 seconds until crisp. Place the fried sage leaves on a paper towel-lined plate and sprinkle with salt. Set aside until ready to use.
Now it’s time to build these bad boys. To assemble each quesadilla: Spread a quarter of the mashed butternut squash onto one half of the tortilla and sprinkle with 1 ounce goat cheese. Crumble 5 fried sage leaves over the goat cheese and top with 1/3 cup grated Fontina. Fold the empty tortilla half over the toppings to close.
Heat a large skillet over medium heat. When hot, add two quesadillas to the pan. (If the pan is too small you’ll have to cook one at a time. Duh.) Cook for about 3 minutes on each side until the cheese has melted and the tortillas are lightly browned and crispy. Repeat with the remaining quesadillas.
Let the quesadillas cool on a cutting board for a few minutes, then slice each one into 3 slices with a very sharp knife. Serve immediately and bask in the glory of melted cheese and compliments.