Start by making the berry filling. Add berries, lemon juice and honey to a small saucepan and place on the stove over low heat. The berries will get juicy and soft, and you can mash them with the back of a wooden spoon. Simmer for 20-25 minutes, stirring often until they have thickened and reduced into a jammy consistency. Set aside to cool.
Make the streusel by combining all the ingredients in a small bowl and mixing together. Set aside.
Preheat the oven to 180C and line a muffin tray with 9 liners.
In a large bowl combine the whole-meal flour, almond flour, ground up oats, sugar, baking powder, lemon zest and salt. In a separate bowl combine all the liquid ingredients. Add the liquid ingredients to the dry ingredients and mix until just combined.
Scoop the batter into the muffin liners, until about halfway fill. On top of that divide the berry filling and then cover the berry filling with the remaining batter. If you want, you can use a toothpick to swirl the filling into the batter for a marbled effect. Top with streusel.
Bake for 18-20 minutes, or until a toothpick inserted into the centre comes out clean.
Let cool in the tray for 10 minutes, before letting them cool completely on a cooling rack.
Store in an airtight container for up to 2 days.