Photo: Brian Kennedy
In the bowl of a standing mixer fitted with the paddle attachment, stir together the flour, cocoa powder, sugar, and salt.
In a glass measuring cup, whisk together the egg, milk, cream, and vanilla until combined. Set aside.
Remove the mixing bowl from the standing mixer and scatter the frozen butter over the dry mixture. Using a pastry cutter, cut the butter into the dry mix until the mixture is pebbly and the butter chunks are lentil size.
Place the mixing bowl back on the mixer, add the wet ingredients, and beat on the lowest or second-lowest speed until the mixture comes together and a dough starts to form. Turn the dough out onto a very lightly floured surface and bring it fully together with your hands, kneading ever so gently. Do not overwork this dough. Form into a disk. Wrap in plastic wrap and refrigerate for at least 30 minutes or overnight.
Place the peanut butter and chocolate in a medium heatproof bowl.
In a small saucepan, heat the cream over medium heat until it just begins to bubble around the edges of the pan. Remove from the heat and immediately pour it over the peanut butter and chocolate. Let stand for 1 minute. Starting in the centre of the bowl and working your way out to the edges, whisk the mixture by hand until it is completely smooth. Whisk in the vanilla until just combined. Set aside to cool to room temperature. The mixture will thicken as it sets.
Line two baking sheets with parchment paper.
Remove the dough from the refrigerator and divide it in half. Rewrap half of the dough and return that portion to the refrigerator. Place the other half on a flour-dusted work surface and dust a rolling pin with flour as well. Roll out the dough (it will be sticky) into a rectangle approximately 10 by 13 inches (25 by 33 cm), about ⅛ to ¼ inch (3 to 6 mm) thick. (If the dough becomes too sticky, return it to the refrigerator to chill.) Cut the dough into 3-by-4-inch (7.5-by-10-cm) rectangles. If you have scraps, you should be able to reroll them at least once and cut more rectangles. Place the rectangles on one of the prepared pans and refrigerate them. Roll out and cut up the second half of the dough, place the rectangles on the second prepared pan, and refrigerate for at least 45 minutes. You should end up with approximately 20 rectangles in total, the same amount on each sheet and an even number altogether.
Place the peanut butter filling in a large zip-tight plastic bag. If it does not feel thick enough to pipe just yet, pop the filling in the refrigerator for 5 to 10 minutes to help it set quickly. Snip a small corner off the bag to create a do-it-yourself piping bag and set aside. Do the same with another plastic bag and the jam.
Remove the first pan of chilled dough. Pipe the peanut butter filling in a Z shape over the top of the rectangles, making sure to leave a ½-inch (12-mm) space along the perimeter. Pipe the jam in an inverse Z shape over the peanut butter filling, again making sure to leave a ½-inch (12-mm) space along the perimeter. Using a pastry brush, brush water along the exposed ½-inch (12-mm) perimeter of the dough.
Remove the second pan of dough from the refrigerator. Carefully place each of these chilled rectangles directly on top of the filling on the first pan of rectangles, lining up the edges of the rectangles. Seal the pop tarts by pressing the dough together along all four edges. Dip the tines of a fork in flour and use the tines to crimp the sealed border of the dough. Using the same fork, prick the surface of each pop tart three or four times to create vents. Place the pan back in the refrigerator for 20 to 30 minutes.
Preheat the oven to 350°F (175°C).
Bake the pop tarts, rotating the pan halfway through the baking time, until the tops of the tarts appear dry to the touch, 12 to 18 minutes. Transfer the pan to a wire rack to cool completely.
In the bowl of a standing mixer fitted with the paddle attachment, mix the icing sugar with the cocoa powder until uniform in colour. Add the milk and the vanilla and keep mixing until the frosting starts to come together; the texture should be thick and almost sandy. Add the cubed butter all at once and beat on medium-high speed until the frosting looks spreadable. If the frosting is too thin, add a little more sugar; if it is too thick, add a little more milk.
Use an offset spatula to frost each cooled pop tart. Top with a pinch of white, yellow, and orange sprinkles, if you like. Allow to set for 15 minutes, then serve immediately.
Cook's tip: as we are well-known peanut butter fanatics, we wouldn’t dream of making these without the peanut butter portion of the filling; however, if you or any loved ones have peanut allergies, you should know that we also love these with just the jam filling (double it up if you are cutting the peanut butter). And other nut-butter and jam combos work well here too; almond butter and blueberry jam are kind of insanely good together in this chocolate pop tart. The pop tarts taste best when eaten within 24 hours.