Mix batter ingredients in pre-sprayed 8x8-inch baking pan; let rest for 10 minutes. Combine cinnamon mixture in a small bowl by mixing with fork.
Top batter evenly with cinnamon mixture. Using fingers, poke topping thoroughly into batter.
Bake by placing in a COLD oven; set temperature to 350 degrees F. Bake 25 to 30 minutes, until lightly browned and firm in center. Cool 10 minutes. Combine icing ingredients and drizzle over warm cake.