Gluten Free Goat's Cheese Pie

Name: Gluten Free Goat's Cheese Pie
Cuisine: European
Ingredients: 50g (1/3 cup + 1 tbsp) buckwheat flour (see note 1); 25g (3 tbsp) starch (corn, potato or tapioca); 25g (3 tbsp) rice flour; ½ tsp salt; 40g (3 tbsp) butter (cold and chopped into small pieces); 1 egg (medium); 125ml (½ cup) sour cream (see note 2); 75g (¼ cup + 1 tbsp) milk; 2 eggs (medium); ¼ tsp tarragon; sea salt and pepper (to taste); 30g (1 oz) goat cheese; handful of spinach