Preheat oven to 350° F.
In a small bowl, combine chopped rhubarb and 1/4 cup sugar. Stir and set aside.
In a large bowl, combine 1/4 cup softened butter and 3/4 cup granulated sugar. Cream together using a hand mixer. Add 3/4 cup milk and 1 egg and beat until smooth.
In a separate bowl, combine 2 cups all purpose flour flour, baking powder and salt. Add the dry ingredients to the wet ingredients and mix until just blended.
Stir in the rhubarb.
Spoon the batter into a greased 8×8 inch pan.
Prepare the streusel topping by combining 1 cup granulated sugar, 2/3 cup all purpose flour, 1/2 cup softened butter and 1 1/2 teaspoons cinnamon in a small bowl. Mix using a fork until large chunks form.
Sprinkle topping over batter.
Bake at 350° for 50 minutes or until golden brown. Remove to a wire rack to cool completely.