Preheat the oven to 170°C (325°F). Line a baking tray with parchment paper and set aside.

In a medium bowl, whisk together 1 1/2 cups whole wheat flour, 1/2 cup vanilla protein powder, 1 tablespoon sugar, and 2 teaspoons baking powder. (If using the optional 1 cup vanilla protein powder, add it now and whisk to combine.)

In a small bowl, stir together 1/4 cup applesauce, 1/4 cup neutral-flavored oil, and 1 teaspoon vanilla extract until smooth.

Add the wet mixture to the dry mixture and stir until a dough forms. If the dough is crumbly or too dry, add milk or water from the 2 tablespoons listed, 1 teaspoon at a time, up to the total amount available, until the dough holds together.

Shape the dough into a ball, wrap it in plastic wrap, and refrigerate for 15 minutes.

Lightly flour a piece of parchment paper. Cut the chilled dough in half. Place one half on the parchment, cover with a second sheet of parchment, and roll the dough to about 1/8-inch (3 mm) thickness.

Using a pizza cutter or sharp knife, cut the rolled dough into 8 equal rectangles. Repeat rolling and cutting with the second half of dough so you have 16 rectangles total.

Arrange 8 rectangles (the bottoms) on the prepared baking tray, leaving space between them. Divide 1/2 cup strawberry jam evenly among the 8 rectangles, placing the jam in the center of each and leaving a clear border around the edges.

Top each jam-topped rectangle with a second rectangle. Press the edges together gently, then press the edges with a fork to seal each pop tart completely.

Bake the pop tarts in the preheated oven for 10–15 minutes, or until the edges are set and the tops are lightly golden. Remove from the oven and transfer to a cooling rack to cool completely.

To make the glaze, combine 1 cup confectioners’ sugar and 1/2 teaspoon vanilla in a bowl. Add milk or water (from the remaining portion of the 2 tablespoons listed) a little at a time until the glaze reaches a spreadable consistency.

Spread the glaze over the cooled pop tarts, leaving a small rim uncoated around the edges. Allow the glaze to set at room temperature before serving.