How to Make It
Dissolve yeast in 1/2 cup warm water in a small bowl; let stand 5 minutes.
Weigh or lightly spoon flours, potato starch, cornstarch, and flaxseed meal into dry measuring cups; level with a knife. Combine flours, potato starch, cornstarch, flaxseed meal, xanthan gum, and salt in a large bowl, stirring with a whisk. Add yeast mixture, milk, buttery spread, and eggs; beat with a mixer at low speed until blended. Fold in cranberries and walnuts.
Spoon batter into a 9 x 5-inch loaf pan coated with cooking spray. Cover with plastic wrap, and let rise in a warm place (85°), free from drafts, 2 hours or until dough has risen almost to top of pan.
Preheat oven to 400°.
Bake at 400° for 30 minutes or until bread sounds hollow when tapped. Remove from pan; cool on a wire rack.