Preheat the oven to 350°F. Lightly spray 12-cup muffin tin with non-stick spray or line it with paper liners. Set aside.
In a medium saucepan, toss together the berries, sugar, flour and lemon juice for the filling. Cook, stirring, over medium heat until the mixture comes to a boil and the berries start to break down and thicken slightly, about 4-5 minutes. Remove from the heat and let cool.
In a large bowl, whisk together the flour and baking powder for the muffins. In another bowl, whisk together the peanut butter, brown sugar, eggs and milk until smooth and well combined. Add this to the flour and stir until just combined. Divide the muffin batter between the 12 cups in the prepared muffin tin. Use a spoon to make a well in the top of each muffin. Place 1 tablespoon of the cooled berry filling into each well.
In a small bowl, stir together the flour, sugar, brown sugar and melted butter for the streusel topping. Using your hands, squeeze the mixture so that it forms clumps. Top the muffins with the streusel, dividing it equally between the 12 muffins. Lightly press it down into the muffin batter.
Bake the muffins for 20-24 minutes, or until they are lightly browned and a toothpick inserted into the center of a muffin comes out clean. Let cool for 5-10 minutes in the muffin tin and then remove them to a wire rack to cool completely. Store the muffins in an airtight container at room temperature for 3-5 days, or freeze for up to 3 months.
If you prefer to just use fruit preserves instead of making the fruit filling, you will need 3/4 cup of jam.