Preheat your oven to 170°C (325°F). Line a baking tray with parchment paper and set aside to prepare for baking.
In a medium mixing bowl, whisk together the whole wheat flour, vanilla protein powder, sugar, and baking powder until evenly combined. Set this mixture aside.
In a separate small bowl, blend the applesauce, neutral-flavored oil, and vanilla extract until smooth and well mixed.
Pour the wet ingredients into the dry ingredient bowl and stir until a cohesive dough forms. If the dough feels too dry, incorporate 1 to 2 teaspoons of ice-cold water. Shape the dough into a ball, wrap in plastic wrap, and refrigerate for 15 minutes to rest.
After chilling, divide the dough into two equal parts. Roll out one portion between two sheets of parchment paper to a thickness of about 1/8 inch. Use a pizza cutter or knife to cut into 8 equal rectangles. Repeat with the second dough portion.
Arrange half of the rectangles on the prepared baking tray. Place a generous spoonful of strawberry jam in the center of each, leaving edges clear for sealing.
Top each jam-filled rectangle with a second rectangle. Press the edges together firmly using your fingers, then crimp around all sides with a fork to ensure a good seal.
Bake the assembled pop tarts in the preheated oven for 10 to 15 minutes, or until the pastry turns a light golden brown. Remove from oven and place on a wire rack to cool completely.
In a bowl, whisk the confectioners sugar, milk or water, and vanilla extract together until smooth. Adjust liquid amount to reach a spreadable consistency.
Spread the glaze evenly over the cooled pop tarts, leaving a small border uncoated around the edges. Optionally, sprinkle with decorations and let the glaze set at room temperature before serving.