Add the butter and olive oil to a medium saucepan placed over medium-low heat. Once the butter is melted, add the garlic and cook for 30 seconds until fragrant.
Turn the heat up to medium-high and pour the heavy cream and milk into the pan. Whisk everything together. Keep stirring until it comes to a boil.
Add the salt, pepper, chili flakes, and parmesan cheese. Continue whisking - the sauce will thicken pretty quickly, so keep it moving. Once the sauce is thickened, remove it from the heat, and set aside.
Nachos
Preheat your oven to 400 degrees F.
Grab a baking sheet and spread the tortilla chips out over the pan in an even layer. Drizzle as much garlic cream sauce as you like over the chips. (You can serve more sauce on the side for dipping too.)
Top with the onions and pepperoni (and other pizza toppings you're using). Sprinkle the shredded cheese all over the nachos.
Bake until the cheese is nice and bubbly and the veggies are warmed through, about 7 minutes. Remove from the oven and serve immediately.
Notes
If you can't find mini pepperonis, you can use the regular-size pepperoni and cut them into quarters.
You can add any of your favorite pizza toppings to these nachos. Play around and find your favorite combination.