To make scone topping: Combine flour, baking powder, 1/4 cup Parmesan, and salt in a large bowl. Mix well. Cut in butter until mixture is crumbly. Add milk and stir just until dough forms a ball.
Turn dough onto a floured surface and knead a couple of times. until smooth. Pat out dough to about a 3/4-inch thickness and cut out 4-inch circles. Gather the dough scraps, press them together, and repeat. You should get about 12 rounds total. Place circles on a lightly floured plate or baking sheet and refrigerate.
Preheat oven to 400 degrees F (200 degrees C). Lightly grease a 9x11-inch baking dish.
To make filling: Heat the butter in a skillet over medium heat. Stir in the onion; cook and stir until the onion has softened and turned translucent, about 5 minutes. Add garlic and cook, stirring, for 2 more minutes, taking care not to burn garlic. If using garam masala and curry paste, add them now (see Cook's Notes).
Add lamb, Worcestershire sauce, brandy, port, and salt and pepper. Cook and stir until lamb is browned and cooked through, stirring frequently. Add peas to skillet and stir.
Pour in 1 cup water or red wine and bring to a boil. Whisk in 1/4 cup flour. Simmer for 5 minutes, stirring frequently, until sauce thickens.
Spread lamb mixture into prepared casserole dish. Cover with circles of scone dough, letting circles just meet at the edges but leaving room for steam to escape. Brush dough with milk, then sprinkle with Parmesan cheese.
Bake in preheated oven until scones are golden brown and filling is bubbly, about 25 to 30 minutes.