Mulberry Lemon Coffee Cake

My spouse is the baker so this is his recipe.  This is his favorite breakfast during mulberry season.

For the topping, into food processor:

2/3 cup whole wheat flour (or spelt or flour of your choice)
2/3 cup pecans (or nut of your choice)
1/2 brown sugar (or sugar of your choice)
5 tablespoons melted butter or oil of your choice (walnut would be nice)
pinch sea salt
zest of 2 lemons

Pulse until a course meal texture and set aside.

For the cake, in a separate bowl, mix:

1/2 cup whole wheat flour
1/2 cup whole wheat pastry flour
1/3 cup quinoa flour
1/3 cup oat flour
1/3 spelt flour
1 teaspoon baking soda
1 teaspoon baking powder
pinch of sea salt

And set aside

In a separate measuring cup, mix:

juice of 1 lemon
add buttermilk to 1 1/4 cups
1 teaspoon vanilla

And set aside.

In a bowl to a stand-up mixer, cream:

4 tablespoons butter or oil of your choice
1/2 cup evaporated sugar
1/2 cup brown sugar
zest of 2 lemons

Add 2 eggs to mixer, (incorporate 1 at a time).

Alternately mix in a third of the flour mix, then a third of liquid, repeating until all incorporated.

Spread mixture into a buttered 9x13 pan. Sprinkle on top 4 cups of fresh mulberries. Then sprinkle on the crumbly topping.  Bake at 350 degrees 40-60 minutes, until a toothpick comes out clean of cake (but you'll still see berries on the toothpick).