Creamy lemon crumble bars are my favorite nut-free, egg-free lemon bars. I love the creamy lemon filling sandwiched between a brown sugar and oatmeal topping and crust.
In a medium bowl, combine the 1 cup all-purpose flour, 1 cup oatmeal, 3/4 teaspoon baking powder, and 1/4 teaspoon salt with a pastry cutter. Add the 3/4 cup brown sugar and the remaining 4 ounces unsalted butter, use the pastry cutter to combine the ingredients until the mixture is crumbly. Spread about 2 cups the oatmeal mixture into your parchment lined baking pan and use a flat smooth surface to press the mixture together and slightly up the sides of the pan about 1/4 inch.
Over a second medium-sized mixing bowl, zest 3 large lemons and then juice them. You will need 1/2 cup lemon juice (pulp included) and juice the last lemon as needed. Add the lemon juice and 1 14-ounce can sweetened condensed milk, fat-free to the bowl. Use a spatula or whisk to stir until the lemon juice and sweetened condensed milk are combined.
Pour the lemon filling over the prepared pan and avoid pouring over the edge of the crust. Use the back of a spoon to spread the filling evenly and leaving a slight border. Sprinkle the remaining filling over the filling and bake on a middle rack for 25-30 minutes. The lemon bars are ready a few minutes after you start to smell the butter and lemon and when the topping looks a light golden brown.
Remove from the oven and allow the lemon bars to cool down for 30 minutes. Use a sharp knife and press down to cut them into 16 pieces (I use a cleaver!). Allow the filling to set in the refrigerator for a few hours but they are tempting to enjoy warm.