In a large mixing bowl, whisk together all-purpose flour and salt until well combined. Cut in cold unsalted butter using a pastry cutter until the mixture resembles coarse crumbs. Slowly add very cold ice water, mixing just until a dough forms. Shape the dough into a rectangle, wrap it in plastic wrap, and refrigerate for at least 2 hours to chill and firm up.

Preheat your oven to 350°F and spread blanched slivered almonds evenly on a baking sheet. Toast the almonds for 10 minutes or until golden brown and fragrant, then let them cool before grinding them in a food processor. In a saucepan over medium heat, combine the ground almonds, granulated sugar, heavy cream, flour, almond extract, and a pinch of salt, stirring continuously for 5-7 minutes until the mixture thickens. Once thickened, remove it from the heat to cool.

Preheat your oven to 375°F if it has cooled down. Dust your work surface with flour and roll out the chilled dough into two rectangles about ¼ inch thick. Spread half of the cooled almond filling onto one rectangle, leaving a small border. Carefully place the second rectangle over the filled one, pressing gently to seal. Bake on a parchment-lined sheet for 25-35 minutes or until the kringle is golden brown and crispy.

Remove the baked Homemade Almond Kringle from the oven and allow it to cool on a wire rack for about 10 minutes. In a mixing bowl, whisk together sifted powdered sugar with enough milk or heavy cream to achieve a smooth, drizzling consistency. Drizzle the sweet glaze over the cooled kringle, and sprinkle slivered almonds on top for added texture and visual appeal before serving.