In a large microwave-safe bowl, melt the butter. Then, add the lemon juice, eggs, sugar, and lemon zest. Whisk until combined.

Place the bowl in the microwave and cook for 1 minute. Remove and whisk thoroughly. Microwave again for 30 seconds, remove, and whisk well. Repeat this process 4-6 more times until the mixture is thick enough to coat the back of a spoon. Whisking well after each heating is key!

Once thickened (like custard), allow to cool and then place into the fridge until ready to use.

In a medium bowl, whisk together the flour, sugar, baking powder, baking soda, and salt. Set aside.

In a separate medium bowl, whisk together the buttermilk, egg, greek yogurt, and vanilla until combined. Then, add the melted butter and whisk until fully incorporated.

Add the dry ingredients to the wet, and fold with a spatula or wooden spoon until just combined (the dough will be sticky). Add the blueberries and very gently fold them in until evenly dispersed. Cover the bowl and place in the fridge to chill for at least 30 minutes.

Once chilled and ready to fry, fill a large, heavy-bottomed pot or Dutch oven with oil, filling ~2” in the pan. Heat on medium-high until it reaches 350F-370F.

Line a wire cooling rack with a thick layer of paper towels.

Once the oil is hot enough, use a small cookie scoop to scoop the dough and drop directly into the hot oil. Add 6-8 donut holes at a time, frying for 2-4 minutes, until crispy. I tossed mine using a fork to continually flip them over during the frying process.

Once finished, use a slotted spoon to carefully remove and transfer to the rack with paper towels. Repeat with the remaining dough.

While cooling, make the glaze by whisking together all of the ingredients in a medium bowl, until smooth. If the glaze is too thick, whisk in 1 tbsp more buttermilk at a time. If it’s too runny, add more powdered sugar.

Dunk each donut hole into the glaze and toss to coat. Set on a cooling rack until the glaze sets.

Once the donut holes are cooled enough to handle, transfer the lemon curd to a piping bag fitted with a long, filling attachment (you could also just dunk into the lemon curd).

Gently inert the pastry filling tip into the donut holes and squeeze some lemon curd inside.

Serve and enjoy!