Rhubarb Coffeecake

Step 1: Preheat the oven to 350°F. Lightly butter a 9X13X2-inch baking pan and line the bottom with parchment paper. Butter the parchment paper.

Step 2: Stir the flour, salt, and baking soda in a large bowl and set aside.

Step 3: Using a mixer set on medium speed, beat the brown sugar and butter in a large mixing bowl for 3 minutes, or until light and creamy. Beat in the eggs one at a time, beating well after each addition. Beat in the vanilla and butter milk. Continue to beat for 2 minutes, or until smooth, occasionally scraping down the sides of the bowl.

Step 4: Mix the flour mixture into the batter one-third at a time, beating briefly after each addition. Fold in the rhubarb until it is well distributed.

Step 5: Pour the batter int the prepared baking pan. Use a rubber spatula to smooth it out to the edges of the pan. The batter will be very thick.

Step 6: To make the topping stir together the granulated sugar and cinnamon in a small bowl. Sprinkle the topping evenly over the batter.

Step 7: Bake the cake for 40 to 45 minutes, or until a toothpick inserted into the center comes out clean. Remove the cake from the oven and transfer to a wire rack. Cool for 1 hour before cutting the cake into squares to serve.