Preheat your oven to 350ºF. Grease an 8X8 baking pan with non stick spray.
In a medium bowl, mix together the flour, oats, salt, baking soda, and both sugars until there are no clumps.
Add the vanilla to the melted butter and stir. Add the melted butter mixture to the dry ingredients and stir until everything is moist. Put half the mixture into the prepared 8X8 pan and press into an even layer. Bake for 15 minutes.
Remove from the oven and set aside. Leave your oven on.
In a mixing bowl, whisk together the sweetened condensed milk, lemon zest, lemon juice, and
egg yolks. Pour over the crust in the baking pan and spread into an even layer. Sprinkle the remaining
crumb mixture over the top. Bake for 22-25 minutes or until lightly golden brown.
Remove from the oven and cool completely. Once cool, cover and refrigerate until ready to eat.