• Preheat oven to 350 degrees F. Adjust rack to middle of the oven and prepare a rimmed 18" x 13" baking sheet. Grease the bottom, then line with parchment paper. Grease parchment paper.
• Whisk dry ingredients in a large bowl; flour, baking powder, baking soda, spices and salt.
• Whisk sugar, oil, eggs, and vanilla together until mixture is smooth. Stir in carrots and currants.
• Fold in flour mixture and mix until just combined. Spread batter in prepared baking sheet. Tap the baking sheet to get out the bubbles and smooth with an offset spatula.
• Bake until center of cake is firm to the touch, about 15 to 18 minutes. Cool in pan on wire rack for 5 minutes. Leave parchment on cake and invert onto wire rack. Allow to cool completely, about 30 minutes.

Assembling the carrot cake with cream cheese frosting.

• Place the first layer on a piece of cardboard lined with foil or parchment slightly larger than the layer. This makes it easier to pick up the cake and press the nuts into the sides.
• While cake is baking, prepare buttermilk cream cheese frosting. You'll need about 4 cups.
• Cut the 18" x 13" sheet cake into four equal pieces, approximately 9" by 6 1/2".
• Place 2/3 of a cup of the frosting on the first layer, then continue with the next two layers. The top of the cake is frosted with about 1 cup of frosting and the sides with the remaining frosting.
• Lift up cake or put it on a sheet pan and carefully press the toasted pecans into the side of the cake. Score the top of the cake into 12 equal portions then top with a tiny marzipan carrot if desired. Chill one hour before serving.
• Store leftover cake, well wrapped in plastic in the refrigerator for up to three days.