21/ Classic Crumb Cake (with Rhubarb if you wish)

OPTIONAL: Rhubarb filling. Mix together in a small bowl: 

• 1 c. chopped rhubarb
• 2 tbl. sugar
• squeeze of fresh llemon

Mix together topping ingredients in a small bowl until uniform:

• ½ c. brown sugar
• ¼ c. granulated sugar
• ¾ tsp. cinnamon
• ¼ tsp. salt
• 1 stick butter, melted
• 1¼ c. flour

Make cake batter: Beat with a mixer until mixture resembles wet sand: 

• 1¼ c. flour
• 6 tbl. softened butter
• ⅔ c. sugar
• ½ tsp. baking soda
• ¼ tsp. baking powder
• ¼ tsp. salt

Beat in until batter is light and uniform:

• 1 egg
• ½ c. sour cream (or whole milk greek yogurt)
• 1 tsp. vanilla

Spoon batter into buttered 8x8" baking pan. Arrange rhubarb if using on top of batter. Crumble topping evenly over top of cake. Bake at 350° for 30-40 minutes or until cake tester inserted comes out with crumbs on it (not wet batter!).