Don’t let the word “Kringle” full you into thinking that this is going to be a difficult recipe to prepare. It is easier then making donuts and much more delicious. This recipe is chock full of walnuts and brown sugar but you can also use a variety of other ingredients such as cream cheese and jam or pecans and cinnamon.
In a large bowl, cut the butter into the flour until the butter is the size of peas. Stir in the sour cream, form into a ball. Cover with saran wrap and refrigerate 8 hours or over night.
For the filling
Combine 1 cup soft butter, brown sugar, 1/2 cup regular walnuts and 1/2 cup of black walnuts
Preheat the oven to 375 degrees. Prepare a cookie sheet by lining it with parchment paper. Roll the dough out as thin as you can get it on the parchment paper into a long rectangle about 24 inches by 12 inches. Cut slices about 4 inches long into the sides of the rectangle at 1/2 inch intervals. Add the filling all the way down the center. Fold each 1/2 inch wide strip towards the center, crisscrossing the filling in a braid-like fashion. Sprinkle with the remaining walnuts. Twist the entire Kringle into a circular shape. Place onto the cookie sheet and bake for 30 minutes. It will come out all gooey and bubbly with sugar running out of it everywhere and you will think you have a disaster on your hands, but it's not, to be sure. Transfer onto a clean plate and let cool for 30 minutes
For the frosting
While the Kringle is cooling, mix together the confectioner's sugar and water and drizzle over the top of the warm danish.