Preheat oven to 300°.
Lightly spoon flours into dry measuring cups; level with a knife. Combine flours, baking powder, and salt in a large bowl; stir with whisk. Cut in butter with pastry blender or 2 knives until mixture resembles coarse meal. Add 1/3 cup water and cream; stir to form a stiff dough.
Roll dough into a 13-inch square on a baking sheet. Score dough into 16 equal squares. Pierce each cracker with a fork. Bake at 300° for 45 minutes or until crisp. Cool on pan.