Preheat the oven to 350°F and coat an 8×8-inch baking pan with baking spray. In a large bowl, combine the flour, oats, baking soda, and salt. Stir in the granulated sugar and brown sugar until well integrated. Blend in the vanilla extract and pour in the melted butter, mixing thoroughly until a cohesive crumble forms. Firmly press half of this crumb mixture into the base of the prepared pan and bake for 15 minutes. While the crust bakes, whisk together the sweetened condensed milk, lemon zest, lemon juice, and egg yolks in a separate bowl until smooth. Once the crust is done, spread the lemon filling evenly over the baked layer. Crumble the remaining oat mixture over the top. Return the pan to the oven and bake for an additional 20 to 22 minutes, or until lightly golden. Allow the bars to cool entirely at room temperature, then transfer to the refrigerator to set. For cleaner slices, chill thoroughly or freeze before cutting. For an elevated presentation, freeze the bars, cut them, and dip the base in melted white chocolate. Arrange on a wax paper-lined baking sheet and keep refrigerated.