Preheat oven to 400°F (200°C) and place a rack in the middle
In a food processor rice the cauliflower florets (it should be evenly chopped but not completely pulverized)
In a large bowl combine 3 cups of cauliflower rice, eggs, almond flour, coconut flour, baking powder, garlic powder, salt and pepper. Mix well
Refrigerate the cauliflower mixture for 5 minutes - this will allow the almond flour and coconut flour to soak up some of the moisture
Take out the fridge and give it another good stir
Line a baking sheet with parchment paper and lightly grease with olive oil
Using your hands form 4 even sized buns (squeezing the mixture so it holds together) and lay onto the lined baking sheet
Sprinkle toppings and lightly press them into the top. With the handle of a spoon/fork/knife the making a big hole in the middle of each bun
Bake in the oven for about 16 to 18 minutes, or until it reaches a bread-like consistency
Turn on the broiler on high, and broil for further 2 to 3 minutes until the top is golden
Remove from the oven and let cool completely on a rack before peeling them off the parchment paper