1Heat oven to 375°F. In medium bowl, mix 1/2 cup all-purpose flour, the whole wheat flour and 1/4 teaspoon salt. Cut in butter, using pastry blender (or pulling 2 table knives through ingredients in opposite directions), until mixture looks like small crumbs. Sprinkle with water, 1 tablespoon at a time, tossing with fork just until flour is moistened. Shape into ball; flatten slightly.
2On floured surface, roll dough into 12-inch round. Fold dough into fourths; place in 9-inch glass pie plate. Unfold and ease into pie plate, pressing firmly against bottom and side; crimp edge. Trim overhanging edge of pastry 1 inch from rim of pie plate. Fold and roll pastry under, even with plate; flute.
3In large bowl, mix cheese and 1 tablespoon flour. Stir in eggs, milk and 1/2 teaspoon salt until well blended. Stir in spinach and bell pepper. Pour into pie crust.
4Bake 15 minutes. Cover edge of crust with strip of foil to keep crust from overbrowning. Bake 15 to 20 minutes longer or until knife inserted in center comes out clean. Let stand 10 minutes before serving.