Preheat oven to 350°F (175°C). Line two cookie sheets with non-stick silicone baking liners or parchment paper.

In a large bowl, combine the whole wheat pastry flour, all-purpose flour, baking soda, and salt. Whisk to combine.

In another bowl, whisk together the granulated sugar, light brown sugar, egg white, apple sauce, and vanilla extract until light and fluffy.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined. The batter might be a little crumbly; if so, add a tiny drop of water at a time until it smooths out.

Fold in the mini chocolate chips.

Drop by level spoonfuls about 1 inch apart onto the prepared baking sheets. Bake for 8-10 minutes, or until lightly golden.

Let the cookies cool on the baking sheets for 5 minutes before transferring them to wire racks to cool completely.

Once the cookies are completely cooled, spread about 1.5 tablespoons of frozen yogurt between two cookies to make a sandwich.

Roll the edges of the frozen yogurt in the colored sprinkles. Place the sandwiches on a platter and freeze until firm, about 1 hour.