1. In a large bowl, beat whites and cream of tartar with a mixer on high speed until whites are foamy.
2. Mix 1 cup sugar, cinnamon, and baking powder. Beating on high speed, gradually add sugar mixture to whites. Then continue beating until whites hold stiff, glossy peaks.
3. Crush crackers into pieces about 1/4 inch across. Fold crackers and walnuts into whites.
4. Line 2 baking sheets, 12 by 15 inches each, with cooking parchment (or lightly oil nonstick baking sheets). Spoon meringue mixture in 8 equal mounds about 3 1/2 inches wide and well separated.
5. Bake in a 300° oven until meringue walnut puffs are lightly browned, about 30 minutes. Let cool on pan about 10 minutes. With a spatula, transfer to racks to cool. If making ahead, package walnut puffs airtight and hold at room temperature up to 1 day.
6. Mix strawberries and cream with sugar to taste and spoon onto the walnut puffs.