Apple Tarte With Hemp Seed Crumb Topping

Name: Apple Tarte With Hemp Seed Crumb Topping
Ingredients: 1 1/2 cup Jeanne's all purpose gluten free flour mix (or same amount of all purpose flour if not gluten free); 1/2 teaspoon salt; 1/4 cup sugar; 110 gr cold butter (1 stick); 1/4 cup cold milk beaten with 1 egg yolk; 2 tablespoons (15gr) granulated sugar; zest of half a lemon; 2-3 medium apples (I used 3 medium winesap apples); 1/4 cup Jeanne's all purpose gluten free flour mix (or same quantity regular flour); 1/4 cup granulated sugar; 1/4 cup unsalted butter, super cold; 3 tablespoons raw hemp seeds; Creme fraiche or whippped cream to serve (optional)