In a large mixing bowl, cream together the sugar and shortening until fluffy and light, about 3 minutes. Add eggs, milk, and vanilla, mixing until combined.

In a separate bowl, whisk together the flour, baking powder, and salt until well combined.

Gradually add the dry mixture to the wet ingredients, mixing carefully with a spatula until just incorporated. Gently fold in the blueberries.

Preheat your oven to 375°F (190°C). Pour the batter into a greased 9x13 inch baking pan.

In a small bowl, mix together the brown sugar, flour, and cold butter until crumbly. Sprinkle over the cake batter.

Bake for 35 to 45 minutes, or until a toothpick inserted in the center comes out clean.

Allow to cool in the pan for 15-20 minutes before serving.