Preheat oven to 350 degrees. Line an 8x8x2-inch pan with parchment paper and set aside.
CAKE: In a medium bowl, sift together 2 cups flour, baking powder and 1/2 teaspoon salt; set aside.
In a large bowl, cream together 1/2 cup butter and granulated sugar, until light and fluffy. Reduce the speed to low, and add the egg and vanilla extract. When combined, alternate adding flour mixture and milk to the bowl, beginning and ending with the flour mixture. Gently fold in pears. Pour the batter into the prepared pan.
STREUSEL TOPPING: In a small bowl, mix 3/4 cup flour, brown sugar, cinnamon and 1/4 teaspoon salt together. Cut in 4 tablespoons butter using a pastry blender or fork until fine crumbs are formed. Using your hands, squeeze together most of the mixture to form large clumps. Sprinkle topping generously over batter.
Bake for 55-60 minutes or until a cake tester comes out clean. Let cool 10 minutes before removing sides of pan. Let cool 15 minutes before serving.