# What You Need:
→ Rhubarb Layer
01 - Fresh rhubarb, trimmed and chopped - 14 oz
02 - Granulated sugar - 2.6 oz
03 - Lemon juice - 1 tbsp
04 - Cornstarch - 1 tbsp
→ Shortbread Base and Crumble
05 - All-purpose flour - 8.8 oz
06 - Rolled oats - 3.5 oz
07 - Unsalted butter, cold and cubed - 5.3 oz
08 - Light brown sugar - 3.5 oz
09 - Salt - 1/2 tsp
→ Custard Layer
10 - Whole milk - 10.1 fl oz
11 - Large egg yolks - 2
12 - Granulated sugar - 2.1 oz
13 - Cornstarch - 2 tbsp
14 - Vanilla extract - 1 tsp
# Directions:
01 - Preheat oven to 350°F. Line a 9-inch square baking pan with parchment paper, allowing overhang on sides for easy removal.
02 - Combine rhubarb, sugar, lemon juice, and cornstarch in a saucepan. Cook over medium heat, stirring frequently, until rhubarb softens and mixture thickens, approximately 8-10 minutes. Transfer to a bowl and allow to cool.
03 - In a large bowl, whisk together flour, oats, brown sugar, and salt. Add cold cubed butter and work into mixture using your fingertips or a pastry cutter until texture resembles coarse breadcrumbs.
04 - Press two-thirds of the crumble mixture firmly into the prepared pan to form an even, compact base. Reserve remaining crumble for topping. Bake for 15 minutes until lightly golden. Remove and allow to cool slightly.
05 - Heat milk in a saucepan until steaming but not boiling. In a separate bowl, whisk egg yolks, sugar, and cornstarch until smooth. Gradually add hot milk while whisking constantly. Return mixture to saucepan and cook over medium heat, stirring continuously, until thickened, approximately 2-3 minutes. Remove from heat and stir in vanilla extract.
06 - Spread cooled rhubarb evenly over the baked base layer. Pour custard mixture evenly over the rhubarb layer.
07 - Sprinkle reserved crumble mixture evenly across the top layer.
08 - Bake for 30 minutes until crumble is golden brown and custard is just set. Remove from oven and allow to cool completely in the pan.
09 - Refrigerate for at least 2 hours. Lift out using parchment paper overhang and cut into 16 bars.
