Chocolate-Filled Buns

"I remember as a child eating croissants with chocolate filling for the holidays. I decided to create the best of everything possible: easy to prepare, wholegrain, soft dough and, most importantly, chocolate. I like to chill the chocolate before forming the buns so that it doesn't melt while working with it." - Christina Erickson, Los Banos, California
Lightly pour the wholemeal flour into dry measuring cups; smooth with a knife. Combine the wholemeal flour, sugar, salt, and instant yeast in a large bowl, mixing well with a whisk.Combine the milk, 1/2 cup water, butter, and canola oil in a microwave-safe bowl; cook in the microwave on high power for 2 minutes, stirring every 30 seconds, until the mixture is warm (100 ° to 110 °). Add the milk mixture to the flour mixture; stir for 1 minute. Add the egg; stir for 1 minute. Lightly pour the bread flour into dry measuring cups; smooth with a knife. Add the bread flour to the yeast mixture; stir until a soft dough forms. Place the mixture on a lightly floured surface; knead for 2 minutes.Place the dough in a large bowl greased with cooking spray; lightly brush the top of the dough with cooking spray. Cover and refrigerate overnight.Preheat the oven to 375 degrees.Place the dough on a lightly floured work surface and press down. Divide the dough into 16 equal portions; shape each portion into a ball. Working one ball at a time (cover with the remaining dough to prevent drying out), roll out the dough into a 5-inch circle. Place approximately 1 1/2 teaspoons of chocolate in the center of the circle. Roll out the dough tightly, like jelly; pinch the seams to seal. Place the buns seam-side down on a baking sheet lightly greased with cooking spray. Tuck the tips under you; cover. Repeat the process with the remaining dough and chocolate.Lightly brush the dough with cooking spray; cover and let rise in a warm place (85 °), draughty, for 40 minutes or until the dough is doubled in size. Lightly brush the tops of the buns with egg white.Bake at 375 degrees for 17 minutes or until they are lightly browned. Cool on a wire rack.