• Preheat oven to 350°F and prepare a 9×9-inch baking pan with parchment paper. Set aside.

Oat Crust:

• In a large mixing bowl, combine oats, flour, dark brown sugar, baking powder, and baking soda. Pour melted butter over the mixture and mix together until crumbly. You do not want to over mix.
• Measure out 2 cups of the crumble mixture, and set aside (for the topping).
• Pour the remaining half of the mixture into the prepared baking dish. Press firmly into the bottom of the pan and into the corners. You can use the bottom of a drinking glass to push the crust down.
• Bake 12-15 minutes, or until golden in color. Set aside to cool while making the lemon filling.

Lemon Filling:

• In a large bowl, add the sweetened condensed milk, lemon juice, egg yolks, lemon zest, vanilla, and salt.
• Mix until smooth.

Assemble the bars:

• Pour the lemon mixture over the top of the baked oat crust.
• With a spatula, spread the 1 ¼ cup of raspberries preserves. It will blend in to the lemon filling a bit, but that is okay. Spread it as evenly as you can.
• Take the remaining crumble and with your fingers, crumble it over the top.
• Bake for 20-25 minutes, or until edges are golden.
• Remove from the oven and allow to cool for 30 minutes. Refrigerate for 1 hour before slicing into bars and serving.