How to Make It
Dissolve sugar and yeast in 1/2 cup warm water in a small bowl; let stand 5 minutes.
Weigh or lightly spoon flours, potato starch, and flaxseed meal into dry measuring cups; level with a knife. Combine flours, potato starch, flaxseed meal, xanthan gum, and salt in a large bowl; beat with a mixer at medium speed until blended. Add yeast mixture, oil, egg whites, and egg; beat at low speed until combined. Increase speed to medium; beat 2 minutes.
Spoon dough onto an 11 x 7-inch baking sheet coated with cooking spray and lined with parchment paper. Lightly coat hands with cooking spray; press dough into an 11 x 12-inch rectangle. Cover with plastic wrap coated with cooking spray, and let rise in a warm place (85°), free from drafts, 30 minutes.
Preheat oven to 400°.
Bake at 400° for 14 minutes or until bottom is crisp. Cool completely. Increase oven temperature to 425°.
Remove casings from sausage. Heat a large skillet over medium-high heat. Add sausage; cook 3 minutes, stirring to crumble. Spread marinara over crust, leaving a 1/2-inch border; top with sausage, cheese, and olives. Bake at 425° for 12 minutes or until crust is golden.