Preheat the oven to 350 degrees F. Line an 8x8 square inch baking dish with parchment paper.In a large bowl, beat together the flour, brown sugar, salt, and Land O Lakes® Butter, until a crumbly dough forms. If the dough seems dry, add 1 tablespoon water.Press 1/2 of the dough into the bottom of the prepared baking dish. To the remaining dough, add the granulated cinnamon and sugar.In a bowl, toss together the blueberries, cornstarch, vanilla, and lemon zest. Spoon the berries evenly over the dough. Dollop the jam over the berries. Sprinkle the remaining cinnamon-sugar dough over the berries. Transfer to the oven and bake for 45-50 minutes, until the crumble is a light golden brown.Let cool completely before cutting into the bars. Keep stored in a sealed container for up to 1 week.