Blueberry Poppy Seed Squares, a unique coffee cake in the Eastern European tradition ~ it's packed with fresh blueberries and crunchy poppy seeds on a buttery shortbread crust. This is one unforgettable snack cake!
Cream the butter and sugar together until light and fluffy. Mix in the flour and salt until just combined. Press it into the bottom of your prepared pan. Chill for 20 minutes, then bake for 12 minutes, just until it starts to turn the faintest golden. Set aside to cool.
Meanwhile put the filling ingredients in a saucepan and bring to a boil, stirring to dissolve the sugar and cornstarch. Turn down the heat and continue to boil for about 15 minutes, or until the blueberries have released their juice and the mixture has thickened a bit. Set aside to cool.
Use your fingertips to mix the streusel topping together. Break up the butter into small bits to create a nice crumb. Set aside.
Stir together the poppy seeds and heavy cream. Spread across the bottom of the cooled crust.
Add the blueberries over the top of the poppy seeds. Top with the streusel.
Bake for 40 minutes, until it is bubbling and just begging to turn golden brown along the edges. Cool and cut into 16 squares.
Notes
Grind poppy seeds in a coffee grinder or high speed blender like Vitamix. If you can't grind them, use them whole.
One of the commenters below suggests using a rolling pin to lightly crush the seeds.
You could theoretically leave out the poppy seed layer and just add some to the shortbread dough and streusel for a more subtle poppy seed presence.
You could use any number of berries in place of the traditional blueberries.