Gather all ingredients.

Bring a large pot of lightly salted water to a boil. Cook spaghetti in the boiling water, stirring occasionally until cooked through but firm to the bite, about 10 to 12 minutes. Drain and transfer to a pasta bowl.

While the pasta is cooking, combine olive oil and garlic in a cold skillet.

Cook over medium heat to slowly toast garlic, about 10 minutes. Reduce heat to medium-low when olive oil begins to bubble. Cook and stir until garlic is golden brown, about another 5 minutes. Remove from heat.

Stir red pepper flakes, salt, and black pepper into pasta.

Pour in hot olive oil and garlic, and sprinkle on Italian parsley and half of the Parmigiano-Reggiano cheese; toss until combined.