Make the streusel: Preheat oven to 400°F; set out two cookie sheets or rimmed baking sheets; combine the flour, brown sugar, cinnamon and nutmeg in a medium-size mixing bowl; add the butter, vanilla and pecans; using a pastry blender, cut the butter into the flour mixture until it is reduced to small bits; crumble and press the mixture between your fingertips until it adheres to itself and forms moist, sandy-textured lumps; set aside.
Make the scone dough: In a large mixing bowl, whisk together the all-purpose flour, baking powder, salt, cinnamon, nutmeg and cardamom; drop in the chunks of butter and, using a pastry blender, cut the chunks into the flour until they are reduced to the size of large pearls; stir in the granulated sugar; add the raisins to the flour along with the liquid mixture and stir to form a dough.
Turn the dough onto a lightly floured work surface and knead lightly about 10 times; divide the dough in half and form each piece into a 6 1/2- to 7-inch round disc; cut each round into 6 pie-shaped wedges; carefully pick up each scone, brush the top with a little of the milk and press a large handful of the streusel mixture on the top; after it is covered with the topping mixture, carefully transfer the scone to the baking sheet, placing the scones about 2 1/2 inches apart.
Bake the scones for 17 to 18 minutes, or until golden and set; cool the scones on the baking sheet for a minute, then remove them to a cooling rack.
Serve warm, or cool thoroughly; store in an airtight container, for up to 3 days (or freeze) and reheat at another time.