In a large mixing bowl, whisk together 2.5 cups of all-purpose flour and 1 teaspoon of fine table salt until combined. Cut in 1 cup of cold unsalted butter until the mixture resembles coarse crumbs. Gradually add 0.5 cup of ice-cold water, mixing until the dough forms a cohesive mass. Shape into a rectangle, wrap in plastic, and refrigerate for at least 2 hours.

Preheat your oven to 350°F (175°C) and spread 1 cup of blanched slivered almonds on a baking sheet. Toast for 8-10 minutes until golden. Allow cooling before grinding. In a saucepan, combine ground almonds, 1 cup of granulated sugar, 1 cup of heavy cream, 0.25 cup of all-purpose flour, 1 teaspoon of almond extract, 0.5 teaspoon of vanilla extract, and a pinch of salt. Stir for 5-7 minutes until thickened and cool.

Preheat the oven to 375°F (190°C). Roll the chilled dough into two 12x18 inch rectangles. Spread the cooled almond filling on each rectangle, then roll jelly-roll style into logs. Shape each log into a horseshoe and place on a baking sheet. Bake for 25-35 minutes until golden brown.

Allow to cool on a wire rack for 10-15 minutes. Prepare the glaze by whisking together 1 cup of powdered sugar and 2-3 tablespoons of milk or heavy cream until smooth. Drizzle over cooled kringle and garnish with additional slivered almonds. Allow to set before slicing and serving.