Put the butternut squash in a saucepan of water and bring to the boil. Boil until tender, then drain and set aside to cool. Meanwhile, put the beetroot in a mini food processor with 2 tbsp yogurt and blitz to a purée. Set aside. Rinse the processor, then blitz the spinach and cooled squash separately with 2 tbsp yogurt each.
Divide the flour between three separate bowls and add 1 tsp baking powder to each. Divide the oil evenly between the three bowls and add a pinch of salt. Add a different purée to each bowl, then mix each to bring together into a dough. Knead each one for a couple of minutes until you have a smooth consistency. Divide each ball of dough into 4 balls.
Flour your surface and roll each ball out to a large circle, similar in size to a dinner plate. Try and get the dough as thin as possible. Put 1 tsp oil in a large frying pan and cook the tortillas over a medium heat for a couple of minutes per side, until they start to blister. You may need to add a bit more oil to the pan as you go. Serve with your favourite fillings.