Slowly whisk the chickpea flour, salt, baking powder, garlic and water until it’s a thick, smooth batter. It will take a while to get the lumps out but keep going until it’s smooth. If you taste it at this point, don't worry! The taste changes completely as you cook it! It's pretty nasty at this stage - you haven't done anything wrong or bought bad flour.
Preheat the oven to 350F/160C and heat an 10” skillet (one where the flat part is 8") with a little oil. When the skillet is hot, pour in the batter, smooth it out across the flat part of the pan and not up the sides, and turn down to a medium heat. Allow the pizza base to cook for a few minutes until you can easily slide a knife under the edges to loosen it the whole way round.
Gently slide it out of the pan and onto a lined baking sheet and put it into the oven. Bake the plain crust at 350F/160C for another 5-10 minutes until the top is fully cooked and browning.
Remove the crust from the oven, raise the heat to 200C/400F and load up the toppings. Put it back in the oven, for about 10 minutes on the lined baking sheet until any cheese is melted and the toppings are cooked. Pull it out of the oven, slice and serve!