📖 Instructions

1. Preheat your oven to 350°F (175°C). Lightly grease a 9x13 inch baking pan. I like to line the pan with parchment paper, leaving an overhang on the sides; this makes it super easy to lift the baked bars out later. Trust me, this little step saves a ton of hassle!
2. In a large mixing bowl, whisk together the flour, powdered sugar, and salt. This ensures everything is evenly distributed before adding the butter.
3. Cut in the cold butter using a pastry blender or your fingers until the mixture resembles coarse crumbs. If you're using your fingers, work quickly to prevent the butter from melting.
4. Add the egg yolk and vanilla extract. Mix until the dough just comes together. Be careful not to overmix, or the crust will be tough. It should form a cohesive ball.
5. Press the dough evenly into the prepared baking pan. Use the bottom of a measuring cup to help smooth it out.
6. Bake the crust for 15-20 minutes, or until it is lightly golden brown. Keep a close eye on it to prevent it from burning; ovens can be temperamental!
7. While the crust is baking, prepare the custard filling. In a large bowl, whisk together the granulated sugar, flour, and salt. This prevents lumps from forming in the custard.
8. In a separate bowl, whisk together the eggs, egg yolks, heavy cream, and vanilla extract until well combined. This will give the custard a rich and smooth texture.
9. Gradually whisk the wet ingredients into the dry ingredients until smooth. Make sure there are no lumps in the mixture.
10. Gently fold in the diced rhubarb. Distribute it evenly throughout the custard.
11. Pour the custard filling over the pre-baked crust. Spread it evenly to ensure each bite has a good balance of crust and filling.
12. Bake for 30-35 minutes, or until the filling is set and the top is lightly golden brown. The center should be just slightly jiggly. If the crust starts to brown too quickly, you can loosely tent the pan with aluminum foil.
13. Let the bars cool completely in the pan before cutting into squares. This will help the filling set properly. I know it's hard to resist, but trust me, patience pays off!
14. Once cooled, lift the bars out of the pan using the parchment paper overhang. Cut into squares and dust with powdered sugar, if desired. Serve and enjoy! These are delightful slightly chilled too.