Blueberry Donut Bars - Fresh Bean Bakery

In a microwave safe measuring cup, heat the milk to 100°F / 38°C. Whisk in the yeast and the sugar. Set aside until the mixture begins to foam. (~5 minutes)
While waiting, add the flour, salt, egg, and butter to the bowl of a stand mixer fitted with the dough hook attachment. When the yeast mixture begins to foam, add it in to the rest of the ingredients.
Knead the dough on low speed for 1 minute to allow the ingredients to come together. Increase the speed to medium-high and knead for an additional 10-20 minutes, or until the dough passes the windowpane test. (This will happen after the dough has cleaned the sides and bottom of the bowl)
Once the dough is done kneading, butter the inside of the bowl, form the dough into a ball and place it back in the bowl. Then cover the mixing bowl with plastic wrap. At this point, you could set the dough in the fridge to rise overnight, or continue with completing the recipe in one day. If doing in one day, set the dough in a warm area and wait for it to double in size (~1 hour.)

While the dough is rising, make the blueberry curd. Add the egg yolk, sugar, blueberries, lemon juice, lemon zest, and salt into a small saucepan.
Whisk the mixture constantly over medium heat, mashing the blueberries as they soften, until the mixture thickens and reaches a temperature of 170°F / 76°C.
Remove the curd from the heat and pass it through a fine mesh into a small bowl. Add in the butter and mix until it has completely melted.
Transfer the curd to an airtight container and store it in the fridge until you're ready to fill the donuts.

Cut out 6 parchment squares that are ~4" each and place them on to a lined baking tray.
Once the dough has doubled in size, punch it down to remove excess air, then transfer it to a clean, lightly floured surface.
Divide the dough into 6 equally sized pieces, roughly shaping them into a rectangle. Use a rolling pin to roll out each piece into a 4" x 2" rectangle, using your hands to gently smoosh the dough into the correct shape and size as needed.
Transfer each donut bar to its own parchment square, then cover the donuts loosely with a towel. Allow them to rise in a warm environment for ~30 minutes, or until they have slightly puffed up the dough springs back slowly when poked.
While the dough is rising, start on the blueberry glaze. Add the blueberries* and sugar to a small mixing bowl. Mash the blueberries, then set the mixture aside.
Once the donuts have puffed up, fill a large saucepan with at least 2" of vegetable or any neutral oil. Heat the mixture to 350°F / 175℃
Carefully place the donuts in to the fryer with the parchment paper (2-3 at a time, depending on what your pan can fit). After ~5-10 seconds, remove carefully remove the parchment from the donuts using metal tongs.
Fry the donuts on each side for 2-3 minutes, or until they are a deep golden brown. You can also check if they are done by making sure the internal temperature is at least 190°F / 87°C.
Remove the donuts from the oil and place them on a wire rack to cool. Fry the remaining donuts.

Add the heavy whipping cream, sugar, and vanilla to a medium-sized mixing bowl. Use a hand mixer or a stand mixer fitted with the whisk attachment to beat the mixture until soft peaks form. Set aside in the fridge until you're ready to fill the donuts.

Once the donuts have cooled to room temperature, finish making the blueberry glaze. Add the powdered sugar into the mashed blueberry mixture and stir until the mixture is cohesive. If the mixture is too thick, add a little bit of water or lemon juice to thin it out. If it is too thin, add some powdered sugar to thicken it up.
Use a sharp knife to poke a hole in the top of each donuts.
Dollop the blueberry curd into the whipped cream, then use a rubber spatula to make a couple of big folds in the cream to slightly combine the curd and cream. Transfer the mixture to a piping bag fitted with a round tip.
Fill each donut generously with the whipped cream & blueberry curd, then dip the tops of the donuts into the blueberry glaze. Allow the glaze to set, then serve immediately and enjoy!

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*If you are using frozen blueberries, microwave them in 10-second intervals until they soften.