Rhubarb coffee cake with rolled oats crumble topping

Made this in Ireland with raisins and apples. Today I made it again, but with rhubarb. I made a double recipe. Here is the recipe below as a single recipe with my changes.

Mix in large bowl
1/3 cup melted margarine
3/4 cup packed light brown sugar
2 large eggs (did put them in this time)
1 cup plain yogurt
1 teaspoon pure vanilla extract

Mix in medium bowl
2 cups all purpose flour
1 teaspoon baking soda
1 teaspoon ground cinnamon
1 tsp baking powder
1/2 teaspoon salt
2 1/4 cups peeled, chopped rhubarb

Crumble Topping
1/2 cup packed light brown sugar
1/2 cup rolled oats
1/2 teaspoon ground cinnamon
2 tablespoons melted margarine

Add dry ingredients to wet and fold in. Sprinkle crumble topping on top of batter.

Took about 38 minutes this time without the convection oven. Use a toothpick to test when done.