Directions

1. In a large mixing bowl, combine flours, sugar, yeast and salt. Add cubed butter; cut it into dry ingredients using a pastry blender until butter resembles coarse, semi-uniform crumbs that are a little larger than pea-sized.
2. In a small bowl, whisk together milk and egg. Add mixture to the flour-butter mixture. Using a rubber spatula, stir together until moistened; turn mixture out onto a clean surface. Working quickly, use your hands to gently knead the mixture until it comes together to form a smooth, yet crumbly dough. Shape into a rectangle; wrap tightly with plastic wrap. Chill dough in the refrigerator at least 4 hours and up to 2 days.
3. To prepare filling, finely blend pecans in a food processor; transfer to a small bowl. Add brown sugar, maple syrup and melted butter; mix together and set aside.
4. After chilling, roll the dough on a lightly floured surface into a 15x8-in. rectangle. Fold rectangle into thirds, like a brochure, bringing the short ends toward the center. Rotate dough 90 degrees, then roll out again into a 15x8-in. rectangle. Repeat the folds again; wrap dough tightly in plastic wrap and chill 20-30 minutes. Repeat the rolling and folding process two more times, chilling 20 minutes between sessions. After the final fold, wrap dough in plastic wrap and chill for a final 20-30 minutes before assembling.
5. Line two 15x10x1-in. baking sheets with parchment paper. Unwrap dough; cut in half. Return one half to the fridge; place the other half on a lightly floured work surface. Roll dough into a 30x5-in. rectangle. Spread half of the filling in an even strip down the center of the dough about 1-1/2 in. wide. Seal the filling inside the kringle by taking one long side of the rectangle and folding it over the filling, pressing gently to adhere. Then, use a pastry brush to brush the remaining unfolded third of the dough with egg before folding the dough over the center. Use your fingers to tightly pinch the seam together along the length of the dough as well as the seams on the short ends.
6. Remeasure dough to be sure it's 30 inches long, stretching to the appropriate length, if necessary. Transfer dough to one of the parchment-lined baking sheets, seam-side down; gently shape into an oval. Tuck and pinch together where the ends of the dough meet, then cover loosely with plastic wrap. Let the kringle proof in a warm spot for 30 minutes or until it has puffed slightly.
7. Preheat oven to 375°; position oven rack in the center. Brush the proofed pastry with egg wash; bake until deeply golden brown, 18-22 minutes.
8. Meanwhile, in a small bowl, whisk together icing ingredients until smooth. Cover; set aside.
9. Remove kringle from the oven; immediately press a clean baking sheet or cast-iron pan to gently compress the pastry to flatten it slightly. Let cool completely. Drizzle or spread the icing over the top of the kringle; let icing set, then slice and serve.