Heat up a pan on low-medium heat. Add 1 tablespoon of butter and 1 tablespoon of avocado oil.
Add chopped garlic and sauté for 30 seconds.
Add peppers and onions. Increase the heat to medium. Season with a little salt and sauté until caramelized, roughly 10 minutes.
Now add tomato paste coriander powder, cumin powder, turmeric powder, and red chili powder.
Cook for only 30 seconds to prevent the spices from burning.
Lower the heat to low-medium. Move the veggies to the side and now add the remaining 2 tablespoon of butter. Allow the butter to melt.
Cook the roux for 1 minute. This will help thicken up the sauce.
Add milk slowly to prevent curdling.
Keep stirring while adding the milk.
The sauce will cook for about 5 minutes and thicken.
Reduce the heat to low. Slowly add 1 cup of cheddar cheese. Keep stirring while adding the cheese to prevent curdling.
Add garam masala.
Your masala sauce is ready.