For prune butter, in a saucepan combine prunes, water, and lemon juice; bring to boiling. Reduce heat. Simmer, covered, 40 minutes. Remove from heat; stir in honey. Cool. Place in a food processor bowl. Process until smooth. Cover and set aside.

In a bowl stir together 2 cups of the all-purpose flour, yeast, and cardamom. Heat milk, 1/2 cup butter, sugar, and salt until warm (120 degree F to 130 degree F). Add to flour mixture along with eggs and vanilla. Beat with an electric mixer on low speed for 30 seconds. Beat on high speed 3 minutes. Stir in whole wheat flour and as much remaining all-purpose flour as you can. On a floured surface, knead in enough remaining all-purpose flour to make a moderately stiff dough that is smooth and elastic (about 6 to 8 minutes). Place in a greased bowl. Cover; let rise until double (about 1 hour). Turn out onto a floured surface. Divide in half. Cover; let rest 10 minutes.

Roll each half into a 12x7-inch rectangle. Spread each with 1/2 cup of the prune butter to within 1 inch of edges. Sprinkle with nuts and cinnamon. Roll up; seal. Place loaves, seam down, in two greased 8x4x2-inch loaf pans. Cover; let rise until nearly double (30 to 45 minutes). Bake in a 350 degree F oven 30 to 35 minutes or until bread sounds hollow when tapped. Remove from pans. Brush with melted butter. Cool. Serve with remaining prune butter. Makes 2 loaves (32 servings).

Transfer remaining prune butter to freezer container; seal, label, and freeze up to 1 month. Thaw overnight in refrigerator before serving. Cool loaves completely. Wrap bread in foil and place in airtight freezer containers or plastic freezer bags; seal, label, and freeze up to 1 month. Thaw bread for 2 hours at room temperature.