Place bread slices on ungreased baking sheets. Broil each pan 3-4 in. from heat until golden brown, 1-2 minutes on each side; let cool. Cut into 1-inch pieces; set aside., Spoon pie filling into a greased 5- or 6-qt. slow cooker. In a large bowl cream butter and sugar until crumbly. Add 1 egg at a time, beating well after each addition. Beat in milk, cinnamon and vanilla (mixture may appear curdled). Gently stir in chocolate chips and bread cubes; let stand until bread is softened, about 10 minutes. Transfer to slow cooker., Cook, covered, on low until set and a knife inserted in the center comes out clean, 2-3/4-3-1/4 hours. Serve warm, with whipped cream if desired.