Preheat the oven to 240C / 220C fan and cut a piece of baking paper the same size as a large large baking sheet.
Put the Greek yoghurt into a mixing bowl. Use the empty yoghurt pot to measure the self raising flour, one-third full of flour. Add this to the mixing bowl and stir together. Crumble in the 50 grams of Castello Traditional Danish Blue and knead to a firm dough. Roll the dough out into a large circle or oval shape on the baking paper, aim for around 30 x 40 centimetres. Transfer the paper to the baking sheet and top with 2 tablespoons of BBQ sauce, then use the back of a spoon to spread it around, pushing it outwards to create a slightly thicker crust in the dough.
Shred the poached chicken breast and mix it with the remaining 2 tablespoons of BBQ sauce. Arrange the sauteed spinach on top of the pizza, followed by the BBQ chicken and then the sliced red onion. Crumble the remaining 75 grams of Castello Traditional Danish Blue on top. Brush the crust with olive oil and drizzle a tablespoon or so over the toppings. Bake for 10 minutes, turning halfway, until the dough has risen and the cheese is bubbling. Let cool for 5 minutes before slicing.