These bars were made with blueberries because I had some plump ones on hand that needed to be eaten, but you can substitute any berry that you like. If you want to make a traditional berry crisp, halve the recipe for the crust. You should also use a smaller pan and/or double the amount of berries, and toss the berries with a couple tablespoons of flour to soak up the excess juices they produce when cooked.
3 cups flour
Mix together the flour, 1/2 cup of the sugar, cinnamon, vanilla and milk. Cut the butter into the mix, and knead into the flour until it begins to look like course crumbs. Squeeze some of the mixture in your hand, it should stay intact and form a ball, but should break apart easily with your fingers. If it won't stay together, add more butter. If it won't come apart, add more flour. Pour half of the mix into a greased 9x13 baking dish. Press down firmly until it forms a crust.
Toss the blueberries, 1/4 cup sugar and lemon juice together. Pour the berries over the crust and spread evenly along the first layer. Sprinkle the rest of the crust mixture over top and lightly press into another layer.
Bake in the oven at 350º 30-40 mintues, or until the crust begins to brown. Allow to cool, and then cut into deliciously imperfect bars of berry goodness.