Cook and stir bacon in a large skillet over medium heat, turning occasionally, until browned, about 10 minutes. Drain on paper towels; reserve.

Bring chicken stock to a boil in a saucepan over high heat. Reduce heat to low; keep warm.

Melt 2 tablespoons butter in a large, heavy-bottomed saucepan over medium-high heat. Add onion and garlic; cook and stir until onion turns golden brown at edges, about 2 minutes. Stir in rice until coated in butter and rice begins to toast, 2 to 3 minutes. Reduce heat to medium; stir in 1/3 chicken stock and continue stirring until rice absorbed liquid and turned creamy. Repeat process twice more, stirring constantly. Stirring in broth should take 15 to 20 minutes in all. When finished, the rice should be tender, yet slightly firm.

Remove risotto from heat; stir in remaining 2 tablespoons butter, Parmesan cheese, and bacon. Season with salt and black pepper before serving.