Step 1

In a small bowl, whisk together the egg yolk and milk. Set aside. Cover and set the egg white aside. If you are making the pop tarts after the dough chills for 1 hour, you can leave the egg whites covered on the counter. Otherwise, cover the egg whites and store the bowl in the refrigerator until you are ready to roll out and make the pop tarts.

Step 2

Combine 2/3 of the flour, sugar and salt in a food processor by pulsing twice to mix. Evenly spread the butter chunks on top. Pulse about 25 times, until no dry flour remains and the dough begins to clump. Use a spatula to scrape down the sides and spread the dough around evenly. Sprinkle on the remaining flour. Pulse about 5 times, until the flour is just mixed in and the dough is crumbly.

Step 3

Pour in the milk and egg mixture. Pulse about 20 times, until the dough has come together. The dough will be a bit sticky, but if you find that it is not coming together, add a bit more flour. Use a spatula and fold and press the dough a few times.

Step 4

Transfer the dough out to a large cutting board. Divide it in half (each half will weigh be about 260 grams). Flatten each half into a rectangle. Wrap tightly in plastic wrap and place in the refrigerator for at least 1 hour before rolling and baking.

Step 5

When the dough is ready, take the dough out from the refrigerator about 10 minutes before you are ready to start rolling. Preheat the oven to 350°F / 176°C. Line a baking pan with parchment paper.

Step 6

Get a large cutting surface clean and dusted with flour. Dust your hands and a rolling pin in flour. Unwrap one piece of the dough and roll it out until it is a rectangle about 8-inches x 15-inches.

Step 7

Next, using a knife, cut the dough into 10 pieces. To do so, cut the dough in half lengthwise. Then evenly cut the dough 4 times across so you have 10 rectangular pieces total (in a 2x5 grid).

Step 8

Brush the entire surface of the dough with the egg whites. Working lengthwise, drop a tablespoon of strawberry chia jam onto 5 of the pop tart rectangles.

Step 9

Using a spatula to help, fold over the other side of the pop tart rectangle so the egg wash is on the inside. Use your fingers and gently push around the sides of each pop tart so it is sealed. Brush egg on the tops of each pop tart.

Step 10

Using a spatula, transfer each pop tart to the pan, leaving about 1-inch between them. Using the tines of a fork, gently push down around the pop tart edges. Prick the top of each tart several times, so that steam can escape while they are baking.

Step 11

Bake for 35-40 minutes, until the are a light golden brown. Remove from the oven and allow to cool on the pan for at least 30 minutes.

Step 12

In a large bowl, mix together the powdered sugar, salt and 1 tablespoons of milk. Slowly add more milk as needed to get a thick, but spreadable frosting. Spread the frosting on completely cooled tarts. Immediately add on sprinkles.