In a large bowl, combine the flour, baking powder, and salt. Cut in the chilled butter until it resembles fine breadcrumbs.

Whisk together the egg yolks and cold water. Pour this into the flour mixture and stir until a dough forms. Wrap in cling film and refrigerate for at least 30 minutes.

Peel and dice the potato and swede. Boil them with diced onion in salted water until tender. Drain and set aside to cool.

Cook the chopped steak over medium heat until browned, seasoning with salt and black pepper. Combine with vegetables and toss in cubed butter. Let cool slightly.

Preheat oven to 200°C (400°F).

Roll out chilled pastry dough and line a pie dish. Scoop in filling and cover with another pastry layer. Seal edges and cut slits on top.

Brush with beaten egg and bake for 25-30 minutes until golden brown.