In a hot pan, pour a good amount of olive oil in. When the oil starts to warm up, add garlic and turn the flame down.
Add the anchovies, if using (don't worry about mincing them as they will dissolve in the mixture). The anchovies should cook in the garlic oil until the garlic becomes brown and the anchovies dissolve.
When the garlic gets light brown, about 5 minutes, add chili flakes until they toast up and then turn flame off. Add more olive oil and salt and pepper for flavor.