📖 Instructions

1. Preheat the oven to 350°F (175°C). This ensures your crust bakes evenly and the custard sets properly. Make sure your oven is *actually* at that temperature! Use an oven thermometer if you aren't sure. I am always paranoid about that!
2. Prepare the shortbread crust: In a large bowl, whisk together the flour, powdered sugar, and salt. If you have a food processor, you can use that too! Make sure everything is evenly distributed. We don't want salty patches in our crust!
3. Cut in the butter: Add the cold, cubed butter to the dry ingredients. Using a pastry blender or your fingers (if you're feeling old school!), cut the butter into the flour until the mixture resembles coarse crumbs. The smaller the butter pieces, the better the crust will be! Chilled ingredients are key, so don't skip this step. I sometimes even freeze my butter for a few minutes before using it.
4. Press the crust into the pan: Press the mixture evenly into the bottom of an ungreased 9x13 inch baking pan. For best results, use the bottom of a measuring cup to flatten and compact the crust. This will give you a nice, even base for the filling. You can also use parchment paper to line the pan for easy removal later.
5. Pre-bake the crust: Bake the crust for 15-20 minutes, or until it's lightly golden brown. Keep a close eye on it to prevent burning! This is a crucial step to ensure the crust doesn't get soggy from the filling. Remove from the oven and let it cool slightly while you prepare the rhubarb filling.
6. Prepare the rhubarb filling: In a medium bowl, combine the diced rhubarb, granulated sugar, and cornstarch. Toss to coat the rhubarb evenly. The cornstarch will help thicken the filling as it bakes. If you are feeling fancy, you can add a splash of vanilla extract here!
7. Spread the rhubarb filling over the crust: Arrange the rhubarb mixture evenly over the pre-baked crust. Try to spread it in a single layer for uniform cooking. Don't worry if it looks a little messy – it will all come together in the oven!
8. Make the custard: In a separate bowl, whisk together the eggs, granulated sugar, vanilla extract, and heavy cream until smooth. The custard should be creamy and lump-free. A little nutmeg? Sure, why not!
9. Pour the custard over the rhubarb: Gently pour the custard mixture over the rhubarb filling. Make sure it evenly covers the rhubarb. If you accidentally create a hole, just gently poke at it with a fork to even it out!
10. Bake the bars: Bake in the preheated oven for 35-40 minutes, or until the custard is set and lightly golden brown. The center should be slightly firm to the touch. If the crust starts to brown too quickly, you can tent the pan with foil during the last 10-15 minutes of baking.
11. Cool completely: Remove the bars from the oven and let them cool completely in the pan before cutting into squares. This is important, as the custard needs time to set fully. If you try to cut them while they're still warm, they'll be a gooey mess. Trust me, I have tried!
12. Chill (optional): For even cleaner cuts, chill the bars in the refrigerator for at least 30 minutes after they've cooled. This will help the custard set even further. However, they are also amazing at room temp!
13. Dust with powdered sugar (optional): Before serving, dust the bars with powdered sugar for a pretty finishing touch. You can also add a sprinkle of cinnamon or nutmeg for extra flavor.
14. Cut and serve: Cut the cooled bars into squares and serve. These are delicious on their own or with a scoop of vanilla ice cream! Enjoy!