How to Make It
In a large, deep skillet of simmering salted water, cook the pasta until al dente. Drain, reserving 1 cup of pasta cooking water.
In a small skillet over medium-high heat, melt the butter. Add the crushed red pepper flakes, minced shallots, sage leaves, salt, and pepper. Whisk until butter begins to bubble and brown. Stir in the pumpkin butter, a splash of pasta water and whisk to combine until saucy. Toss with cooked pasta. Garnish with grated Parmigiano-Reggiano.