Preheat the oven to 350°F.
Line a baking sheet with a silicone baking mat or parchment paper; if using parchment, lightly spray it with oil to prevent sticking.
In a medium bowl, combine the light cream cheese, part-skim sharp cheddar, grated Parmesan, and sliced scallions. Use a small spoon or spatula to fill each jalapeño half with the cheese mixture.
In a medium bowl, whisk together the unbleached all-purpose flour, baking powder, and kosher salt. Add the non-fat plain Greek yogurt and mix with a fork or spatula until the mixture forms small crumbles.
Lightly dust a work surface with flour, transfer the dough to the surface, and knead a few times (about 15 turns) until the dough is smooth and tacky but not sticky; it should not stick to your hand when you pull away.
Dust the work surface and a rolling pin with additional flour.
Roll the dough out thin into a rectangle about 13 x 9 inches, then slice the dough into 1/2 inch-thick slices.
Wrap the dough around each filled jalapeño half, leaving a small gap for the candy eyes, and place them on the prepared baking sheet. Repeat with the remaining jalapeños and dough.
Brush each wrapped jalapeño with the beaten egg white and bake for 30 minutes, until the dough is golden and the peppers are hot.
Press candy eyes onto the exposed filling of each popper.