What's for Dinner?

This dinner was a big hit in my house. Even my 2 year old ate every last noodle on her plate. And it was so simple to make! Makes 8 servings.

Ingredients
6 tablespoons unsalted butter, divided
1/2 cup finely chopped onion
6 cloves garlic, coarsely chopped
1 cup chicken stock
2 tablespoons chopped fresh rosemary
1 (16 ounce) package spaghetti
1/4 cup grated Parmesan cheese
kosher salt and cracked black pepper to taste

Directions
Melt 4 tablespoons of butter in a large skillet over low heat. Add the onions; cook and stir until they turn a deep brown, about 10 minutes. Stir in the garlic, and cook for 2 minutes, until fragrant. Mix in the chicken stock and rosemary, and increase the heat to medium-high. Cook until reduced by 1/3, about 8 minutes.
Meanwhile, bring a large pot of lightly salted water to a boil. Add the spaghetti pasta, and cook until tender, about 8 minutes. Drain, then add noodles to the sauce in the skillet. Stir in the remaining butter and Parmesan cheese. Season with salt and pepper.
Serve in a large bowl family style, or place about 1 cup of pasta in a large mug or small bowl. Insert a dinner fork in the center of the pasta and twirl the fork around, holding the mug steady. The pasta will wind up tighter and tighter as you turn. Remove the fork and immediately turn the pasta out onto a dinner plate or shallow bowl. Garnish with extra cheese and rosemary sprigs.