Mix 1 1/2 cup flour and 1/2 teaspoon salt together in a large bowl. Rub egg yolks and cold butter into the flour mixture until it forms fine crumbs. Add water a little at a time just until dough starts to form and stick together. Wrap dough with plastic wrap and allow to rest in the refrigerator, about 30 minutes.
Roll pie dough out on a well-floured surface and place in 9-inch deep-dish pie plate.
Preheat oven to 350 degrees F (175 degrees C).
Combine apples, 3/4 cup sugar, 2 tablespoons flour, mulling spices, and pinch of salt in a large bowl; mix well to combine. Place apple mixture in prepared pie shell.
Cream 1/2 cup softened butter and 1/2 cup sugar together in a bowl with an electric mixer. Stir in 3/4 cup flour, oats, cinnamon, and pinch of salt. Sprinkle the topping mixture over the apples.
Bake pie in the preheated oven until crust and topping are golden brown and filling begins to bubble, about 1 hour.