In a large mixing bowl, whisk together the all-purpose flour and fine table salt. Cut in the cold unsalted butter using a pastry cutter until the mixture resembles coarse crumbs. Gradually add the ice water, stirring until the dough forms. Shape the dough into a rectangle, wrap it in plastic wrap, and chill it in the refrigerator for at least 2 hours or overnight for best results.

While the dough chills, preheat your oven to 375°F. Toast the blanched slivered almonds in a dry skillet over medium heat until golden, about 5-7 minutes, then allow them to cool. Next, grind the toasted almonds finely in a food processor. In a saucepan, combine the ground almonds, granulated sugar, heavy cream, all-purpose flour, almond extract, vanilla extract, and pinch of salt. Cook over medium heat until thickened, stirring continually, for about 5-7 minutes. Allow the filling to cool completely.

Once both the pastry dough and almond filling are ready, take the chilled dough and roll it out on a well-floured surface into two 12x18-inch rectangles. Spread the cooled almond filling evenly over the dough, leaving a border around the edges. Carefully roll up each rectangle jelly-roll style, forming a horseshoe shape. Place the kringles onto a parchment-lined baking sheet for easy transfer.

Place the assembled kringles in the preheated oven and bake for 25-35 minutes, or until they turn a beautiful golden brown and the internal temperature reaches 200-210°F. As they bake, your kitchen will be filled with an irresistible aroma. Once done, cool the kringles on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.

While the kringles are cooling, prepare the icing. In a bowl, whisk together the sifted powdered sugar, milk or heavy cream, and optional almond extract until smooth. Drizzle the glaze generously over the cooled kringles and garnish with extra slivered almonds for added crunch. Allow the glaze to set before serving your exquisite homemade almond kringle!