Heat oven to 375°F. Grease cookie sheet with shortening or cooking spray. Reserve 1 tablespoon of the cereal.
In large bowl, mix remaining cereal, the flours, brown sugar, baking soda, cream of tartar and salt. Cut in butter, using pastry blender (or pulling 2 table knives through ingredients in opposite directions), until mixture looks like coarse crumbs. Stir in raisins.
In small bowl, beat egg and buttermilk with wire whisk until well blended. Reserve 1 tablespoon buttermilk mixture. Stir remaining buttermilk mixture into dry ingredients, stirring just until mixture is moistened. On floured surface, knead dough 5 or 6 times until dough is combined and holds together.
On cookie sheet, shape and press dough into 7-inch round. Cut large X, 1/4 inch deep, into top of dough, using sharp knife. Brush top of dough with reserved buttermilk mixture; sprinkle with reserved cereal.
Bake 30 to 35 minutes or until top is golden brown and loaf sounds hollow when tapped. Cool slightly before serving.