Note: it is important to work the dough as little as possible. Work quickly to kneed and fold the dough and only the number of times called for. Butter should be frozen solid. It is important that work bowls and ingredients be as cool as possible. Refrigerate the ingredients until ready to actually incorporate into the recipe.
Heat oven to 425°F. Adjust rack to middle of oven.
Score and remove half of wrapper from each stick of frozen butter. Grate the unwrapped portion of the butter on the large holes of a box grater.
Grate a total of 8 tablespoons.
Melt 2 tablespoons of remaining ungrated butter and set aside. Save the remaining butter for another use.
Whisk together milk and sour cream, and Rodelle Vanilla Beans, split and scraped in a medium bowl. Whisk the flour, ½ cup sugar, baking powder, baking soda, salt, and lemon zest in another medium bowl. Add the frozen grated butter to the flour mixture and toss with your fingers until thoroughly coated.
Add milk mixture to flour mixture; fold with spatula until just combined. With rubber spatula, transfer dough to liberally floured work surface. Dust surface of dough with flour; with floured hands knead the dough 6 to 8 times, until it just holds together in a rough ball, adding flour as needed to prevent sticking.
Roll dough into an approximate 12-inch square. Fold dough into thirds, like a business letter, using a bench scraper or metal spatula to release dough if it sticks to the work surface. Lift short ends of dough and fold into thirds again to form an approximate 4-inch square.
Transfer to a plate lightly dusted with flour and chill in freezer for 5 minutes.
Transfer dough to a floured work surface and roll into an approximate 12-inch square again. Sprinkle the raspberries and white chocolate chunks (or chips) evenly over the surface of the dough and gently press down until slightly embedded in the dough. Using a bench scraper or metal spatula, loosen the dough from the work surface. Roll the dough, pressing to form a tight log. Lay it seam-side down and press the log into a 12 by 4-inch rectangle. Using a sharp, floured, knife, cut the rectangle crosswise into 4 equal rectangles. Cut each rectangle diagonally to form 2 triangles.
Transfer to parchment-lined baking sheet.
Brush tops with melted butter and sprinkle with Rodelle Gourmet Vanilla Sugar. Bake until tops and bottoms are golden brown, about 18-25 minutes.
Transfer to a wire rack and let cool 10 minutes until ready to serve.
