Preheat your oven to 350°F. Line a large rimmed baking sheet with unbleached parchment paper and set it aside.

In a large bowl, place the flour, cornstarch, nonfat dry milk, oat flour, baking soda, baking powder, salt, oats and sugar, and whisk to combine well.

Create a well in the center of the ingredients in the bowl and add the yogurt, oil, vanilla, egg, and water, and mix to combine. If necessary to bring the dough together without crumbling, add more water by the teaspoonful. The dough will be sticky and somewhat stiff, but not dry.

Transfer the dough to a lightly floured surface and roll it out into a rectangle about 1/4 inch thick.

Using a sharp knife or pastry wheel, trim any rough edges of the dough and cut out 4-inch squares, gathering and rerolling scraps as necessary.

To shape the bars, place about 2 tablespoons of strawberry preserves down the center third of each square of dough, and fold the ends over each other to cover the filling. Pinch the ends of each bar together to seal.

Place the shaped bars about 2 inches apart from one another on the prepared baking sheet.

Place in the freezer or refrigerator to chill until firm (about 15 minutes). This will help prevent the filling from leaking out of the dough during baking.

Remove the baking sheet from the refrigerator or freezer, and place it in the center of the preheated oven.

Bake until the bars are very lightly golden brown and slightly darker around the edges, about 15 minutes.

Allow the bars to cool on the baking sheet until firm. If any filling has leaked out (and likely some will), once it’s cool, the preserves can be peeled off the parchment paper.