Heat 4 cups of broth in a separate pot and maintain a gentle simmer over medium heat.

In a large heavy-bottomed pot, melt 2 tablespoons of butter with 2 tablespoons of olive oil over medium heat.

Add the diced onion and cook for 3 to 4 minutes until translucent, then stir in the minced garlic and cook for 30 seconds.

Add 1.5 cups of Arborio rice and toast, stirring constantly, for 1 to 2 minutes until the edges become translucent and nutty in aroma.

Pour in 1 cup of warm broth and cook, stirring frequently, until nearly all liquid is absorbed, about 3 to 4 minutes.

Add the remaining broth in 1 cup increments, stirring frequently and waiting until liquid is mostly absorbed before each addition, for about 18 to 20 minutes total.

Taste the rice to ensure it is creamy with a slight al dente bite; it should flow like lava on the plate.

Remove from heat and stir in the remaining 2 tablespoons butter and 0.75 cups grated Parmesan until melted and combined, then season with salt and pepper.

Garnish with fresh parsley if desired and serve immediately to preserve the creamy texture.