Preheat oven to 200 °C /392 °F fan. Cover a baking tray with parchment paper and heat it up in the oven. If you later put the pizza dough on the already heated baking sheet, the pizza base will be particularly crispy.
Knead flour, 2 tsp. baking powder, a pinch of salt and 180 ml (0.7 cups) water on a well floured work surface to a smooth dough. If necessary, add a little more flour until you have a smooth and beautiful dough. Put it aside for a short time, but it does not have to rise, as there is no yeast in the dough.
Rinse the cooked chickpeas and place in a large mixing bowl. Chop the chickpeas with a hand blender or fork (Please do not puree the chickpeas completely, just "chop/mash" them a little).
Peel and chop the onion and a clove of garlic and add to the mashed chickpeas. Wash 2 stalks of celery, dice finely and also mix in. Stir in 2 tbsp. apple cider vinegar, 1 big tbsp. tahini and season with salt and pepper.
Defrost spinach slowly in a pot or microwave, drain water and squeeze the spinach with your hands. Season the spinach with 1 tsp. soy sauce (or salt).
Let melt the margarine in a pot. Using a whisk, stir in the flour and gradually add the plantbased milk. Also stir in the yeast flakes and 1 tsp. of hot mustard and whisk until creamy.
Roll out the dough on a well floured work surface.
Place the pizza base on the hot baking tray. Brush the edge of the pizza dough with a little plantbased milk. This gives the pizza a nice golden baked color. Pre-bake the pizza base in the oven at 200 °C /392 °F fan for 10-12 minutes (without topping) until the edges begin to brown.
Get the hot pre-baked pizza base out of the oven. Heat the béchamel sauce again, stir until creamy (if necessary, stretch with a little water) and spread half of the béchamel sauce over the pizza. Then spread the chickpea topping and spinach over the pizza and pour the rest of the béchamel sauce over the pizza.
Bake the topped pizza at 200 °C /392 °F for another 10 minutes. Now your pizza is ready to enjoy!