01 -
Bring a large pot of salted water to a boil. Add spaghetti and cook according to package instructions until al dente, about 9 to 10 minutes. Reserve 1/2 cup of pasta water before draining. Drain and set aside, tossing with a tiny bit of oil to prevent sticking if desired.
02 -
Heat a large deep skillet over medium-high heat. Melt 1 tablespoon of butter and add olive oil if needed. Add ground beef and cook 5 to 7 minutes, breaking up any clumps, until evenly browned. Drain excess fat for a balanced sauce consistency.
03 -
Add diced onion to the skillet and sauté for 3 to 4 minutes until translucent. Stir in minced garlic and cook approximately 30 seconds, just until fragrant.
04 -
Add the remaining 2 tablespoons of butter, Italian seasoning, garlic powder, onion powder, salt, black pepper, and red pepper flakes if using. Stir continuously for 1 minute to properly infuse flavors.
05 -
Pour in the heavy cream and beef broth (or reserved pasta water). Stir and use a wooden spoon to deglaze and incorporate any bits from the pan base. Allow mixture to simmer for 3 to 4 minutes until it begins to thicken.
06 -
Reduce heat to low. Gradually add shredded cheddar a handful at a time, stirring until each batch melts. Add grated Parmesan and stir until the sauce is smooth. Adjust consistency with a splash of reserved pasta water if needed.
07 -
Add drained spaghetti to the skillet. Using tongs, gently toss for 2 to 3 minutes to evenly coat pasta with the sauce and distribute beef.
08 -
Remove skillet from heat and allow pasta to rest for a couple of minutes to let the sauce set and thicken slightly. Serve hot, garnished with chopped parsley or green onions if desired.