Oatmeal Plum Streusel Breakfast Cake

When I know that in my kitchen there is some kind of fresh streusel cake that I plan to eat for breakfast I, actually, can never wait until breakfast. In some cases I can even predict that a cake like this will never see tomorrow. Because it's is so good. It's a perfect mixture between cooked oatmeal and a fruit salat combined in a cake with streusels on top. Not too sweet. Not too heavy. But too yummy. 
And another good thing about this cake is that you can add to it whatever you wish. You could add some spices like ground ginger, nutmeg or cinnamon to make the cake more cozy. Or you might even want to replace the plums with any fruits you like, depending on the season, like cherries, apricots or figs. It's up to you.

Oatmeal Plum Streusel Breakfast Cake

1 cup sugar
2 eggs
2 tsp salt
1/2 cup oil
1/2 cup milk or water
2 cups flour (if you want the extremely healthy version of a breakfast cake, use whole wheat or whole spelt flour. I was using regular white spelt flour.)
2 cups oats
2 tsp baking powder
+ about 2 cups plums, in thin slices (I added frozen plum slices to the batter, but I think fresh plums would be perfectly fine too)

Preheat the oven to 175C. Line a approximately 8 x 12 inch - baking pan with baking paper. Whisk together sugar, eggs and salt. Whisk in oil and milk. Add the dry ingredients and whisk well until you have a thick and moist mixture. Gently fold in about two thirds of the plums. Pour the batter in the lined pan and smooth the top. Arrange the remaining plums on the top. Now prepare the streusel mixture...

60gm sugar
60gm very soft or melted butter
100 - 150gm white flour (it depends on what consistency you want the streusels to have, I wanted them to be very crumbly, not soft, so I added much more flour)

Combine the ingredients for the streusels and make the mixture very crumbly using either a hand mixer on low speed or your fingers or a fork. Arrange the streusel mixture on top of the cake. Place the baking pan in the oven and bake for about 55 - 65 minutes until done and nicely browned. Let cool for a few minutes, then remove from the pan and let cool completely.