For the cranberry-lemon juice: Cook the cranberries, lemon juice and sugar in a medium saucepan over medium to medium-low heat, stirring occasionally, until the cranberries soften and begin to burst, 10 to 12 minutes. Use an immersion blender to puree the mixture until smooth inside the saucepan. Cool while you make the crust.
For the crust: Preheat the oven to 350 degrees F. Grease a 9-by-13-inch baking dish with nonstick cooking spray and line with parchment paper, leaving at least 2 inches of excess on either side to help you unmold the bars later.
Cream the butter, confectioners' sugar and vanilla in the bowl of an electric mixer fitted with the paddle attachment, until light and fluffy, 4 to 5 minutes. Add the all-purpose flour, almond flour and salt and mix on low speed until the mixture comes together. Scrape the bowl well, then mix on low speed again.
Crumble the crust into the prepared baking dish and carefully press into an even layer with your hands or the bottom of a measuring cup.
Bake until lightly golden brown at the edges, 15 to 17 minutes. Cool completely.
For the filling: Whisk the cooled cranberry-lemon juice mixture with the eggs, egg yolks and sea salt in a large bowl until well combined. Add the melted butter and whisk well to combine. Pour the filling into the cooled crust. Gently transfer to the oven and bake until the center of the custard sets, 24 to 28 minutes. Cool to room temperature, then chill for at least 2 hours before slicing and serving.