Ingredients:
Rhubarb Curd:
150 g Eggs
120 g Rhubarb
75 g Sugar
30 g Water
22 g Lemon Juice
60 g Butter (sliced and at room temperature)
1 g Salt
5 g Poppy Seeds
5 g Beet Powder
Custard Linzer Cookies:
170 g Butter (room temperature)
100 g Sugar
150 g All-purpose flour
92 g Custard Powder (I used Newa Nutrition's)
2 g Salt
30 g Egg Yolk
Topping:
10 g Powdered Sugar
Instructions:
Roughly chop rhubarb and add to blender along with the lemon juice and water. Puree and strain into a large bowl with a sieve lined with a dish cloth. Wring out as much rhubarb/lemon juice as possible, and discard the dried rhubarb remains.
Add to juice to a large saucepan along with sugar. In a large bowl whisk eggs and salt until no egg whites are visible, combine with rhubarb and sugar in the saucepan.
In another large bowl (or the same one cleaned out) add your sliced butter, poppy seeds and beet powder. Cover with a sieve and set aside.
Heat saucepan over medium-high heat, whisking constantly until thickened enough to coat the back of a spoon. Remove from heat and pour in the bowl lined with the sieve, and whisk it all together. Chill in a shallow baking dish until ready to use.
To make the sugar cookies, grab a stand mixer fitted with a paddle attachment. Add your butter and sugar, and cream until pale and fluffy. Add egg yolk, mix to combine, scraping down the bowl as needed.
Add all-purpose flour, custard powder, and salt, and beat until beginning to come together. Remove to a counter and kneed briefly to bring it together into a disc. Wrap it up and refrigerate for 30 minutes to make it easier to work with.
Remove the chilled dough and on a floured surface roll out to a thickness of 6 mm (1/4"). Using a scalloped cutter, cut out the cookie shapes, folding the dough back up and rolling it out as you work your way through it, just try not to work it too much.
Line up your cookie cutouts in pairs ensuring you have an even number, and cut out the peekaboo window using a small scalloped cutter, or the nozzle of a piping bag.
Place on a lined sheet tray and freeze for 20 minutes. Preheat oven to 150ºC (300ºF).
Remove from freezer and bake for 12 minutes or until golden brown and no longer wet looking. Cool to room temperature.
Remove the rhubarb poppy seed curd from the refrigerator and fill a piping bag, pipe a nice blob in the middle of the bottom pieces (the no peekaboo hole ones) and spread out almost to the edge with an offset spatula. Dust the tops with powdered sugar, before gently sandwiching them onto the tops of rhubarb poppy seed curd bases. Admire for a second and then enjoy!