Preheat the oven to 375 F. Butter a 9" springform pan, or a baking dish, and line with parchment.
With a mixer, cream the butter together with the sugar until light and fluffy. Add the eggs, one at at time.
Add the almond and vanilla extract, along with the milk.
In a separate bowl, combine the flour, baking powder, and salt. Whisk to combine, then add to the wet mixture along with the ½ cup slivered almonds. Mix just to combine.
Spread the mixture into the prepared pan and press the blackberries into the top of the batter, which should be thick.
In a small bowl, combine the brown sugar, flour, and cinnamon for the topping. Use a fork to combine, then cut in the butter until crumbly. Mix with the ¼ cup slivered almonds and sprinkle overtop of the batter.
Bake for 45-50 minutes, or until a cake tester comes out clean from the center of the cake.
Recipe by The Kitchen Paper at http://c02.ddd.mwp.accessdomain.com/blackberry-almond-coffee-cake/