Preheat oven to 350°F (180°C).

In a large mixing bowl, beat eggs, oil, and sugar at high speed for 5–7 minutes. Reduce speed to low; add almond flour and 1 cup potato starch and mix just until combined. Divide evenly between 2 greased 8- x 4-inch loaf pans.

In a small bowl, combine jam and 1 teaspoon potato starch. Divide between both pans. Using a knife, marbleize jam mixture into batter with a swirling motion.

Bake for 50 minutes, or until toothpick inserted in center comes out clean. Remove from oven to cool.

Once cooled, remove loaves from pans and slice into thin slices, about a quarter-inch thick. Place sliced biscotti onto lined baking pans and return to oven. Lower heat to 325°F (170°C) and bake for approximately 25–30 minutes, or until lightly browned and desired crispiness is achieved. Allow to cool.

Combine glaze ingredients in small mixing bowl; mix until smooth. Add more confectioners’ sugar if glaze is too thin or a few drops of water at a time if glaze is too thick.

Drizzle glaze over biscotti and allow to set.