Begin by preheating your oven to 350°F (175°C). In a mixing bowl, cream together softened butter and 1/4 cup of sugar until light and fluffy. Gradually add flour and baking powder until the mixture resembles coarse crumbs. Press this mixture evenly into the bottom of a greased baking dish and bake for about 15 minutes until lightly golden.

While the crust is baking, prepare the blueberry curd. In a saucepan, combine fresh blueberries, 3/4 cup of sugar, and lemon juice over medium heat. Cook until the blueberries begin to break down and release their juices. Use a fork or potato masher to mash the blueberries into a puree.

Remove the blueberry mixture from heat and let it cool slightly. In a separate bowl, whisk together eggs until frothy. Gradually mix in the warm blueberry puree. Pour this mixture over the pre-baked crust, ensuring an even layer.

Return the baking dish to the oven and bake for an additional 20-25 minutes, or until the curd is set and the top is slightly firm to the touch. Allow it to cool completely before slicing into bars.