Preheat the oven to 180 °C top/bottom heat.

Grease a round cake tin (Ø 20–22 cm) with vegan butter and dust lightly with flour.

Peel the carrots and grate them finely.

In a large bowl, cream the vegan butter, sugar, vanilla sugar, and salt with a hand mixer or stand mixer until light and fluffy.

Add the grated carrots and mix briefly to combine.

In a separate bowl, sift together the flour and baking powder.

Add cinnamon and ground hazelnuts to the sifted mixture and whisk to combine.

Fold the dry ingredients into the carrot mixture and stir only until a uniform batter forms. Do not overmix.

Transfer the batter into the prepared cake tin and smooth the surface with a spatula.

Bake for 35–40 minutes. Insert a toothpick in the center: a few moist crumbs are fine, but no wet batter should stick.

Let the cake cool in the tin for at least 1 hour before removing it carefully. Place on a plate and allow to cool completely.

Place vegan cream cheese in a bowl.

Sift in the powdered sugar and add the lemon juice.

Whisk until smooth and creamy. Refrigerate until ready to use.

Place the cooled cake on a turntable or keep it steady on a flat surface.

Add the cream cheese frosting on top of the cake in the center.

Using a metal spatula, spread the cream outward while slowly rotating the cake.

Continue rotating and smoothing in circular motions to create the spiral design.

Sprinkle the chopped hazelnuts around the edge of the cream to form a decorative border.

Chill the cake for at least 30 minutes before serving, so the cream can set slightly.