To ensure even baking all ingredients (except fruit) should be room temperature.
Preheat the oven to 350F.
In a large bowl, sift flour and baking powder. Add sugar and pieces of soft butter.
Using your fingers or a pastry cutter, mix all the ingredients until they form small crumbs.
Set aside 3/4 cup of this mixture. To it add cinnamon and stir. This will be the crumb part of your cake. Keep it in the fridge until the whole cake is assembled.
In a separate bowl, mix eggs and milk until well blended.
Add this liquid to the flower and stir only until all the ingredients combine. Do not over mix. It will result in a dense and rubbery cake.
Add frozen berries and mix delicately.
Grease the 9 x 5 loaf pan with soft butter. Additionally, either sprinkle it with plain bread crumbs or cut an overlapping piece of parchment paper and line the pan with it, making sure that longer ends stick out of the pan.
Pour the dough into the pan and smooth the top out with a spatula.
Sprinkle the cake with the 3/4 cup of the flour/butter/cinnamon crumb mixture.
Bake the cake in the 350F oven for 60 min. or until the toothpick inserted into the center of the cake comes out dry.
Cool this cake in the pan.