Preheat the oven to 170 degrees C and grease and line your cake tins.
Grate your carrots and place them in a medium sized bowl. Leave to the side.
Place the flour, baking powder, bicarbonate of soda, cinnamon and ginger into a medium sized bowl and mix until well combined. Leave to one side.
Place the light brown sugar, oil, eggs and vanilla extract into a large bowl or the bowl of your stand mixer and mix until light and frothy, about 2 minutes on med-high speed.
Add in the flour mix and mix until well combined and smooth.
Add in the carrots and mix on low until well incorporated.
Split between the baking tins and place in the oven for 30-40 minutes. (If you're making 2 plain 8inch cake layers this will be closer to 40 minutes, possibly 45, but since I made a 6inch it took around 35 minutes).
Cake is done when risen, golden on top and an inserted skewer comes out clean.
Leave the layers to cool in the tins for at least an hour before transferring to a wire rack to cool completely.
Once chilled, make the frosting. Place the cream cheese and butter into a medium sized bowl and beat until light and fluffy.
Add in the sifted icing sugar, starting on a low speed to avoid the icing sugar cloud, begin to combine the ingredients. Once the mixture starts coming together turn the mixer up to med-high and beat until light and smooth. Add in the vanilla extract and mix until well incorporated.
This is how I made my topsy turvy cake: I placed the large layer bottom side up onto a cake board and placed a light layer of cream cheese frosting on top and around the edges. I placed the smaller layer top side up on a plate and gave it a crumb coat then placed both cakes in the fridge overnight. Keep any leftover frosting to stick the top tier onto the bottom tier.
If you're just making 2 eight inch cakes, place the first cake top side up on a plate/cake board and spread some frosting on the top. Place the second layer on top of the first, bottom side up to ensure a smooth top. Frost the top with a small offset spatula and the sides with a large straight spatula.
To cover my cake in fondant, I brushed a mixture of warm water and apricot jam over the crumb coated cakes and rolled the fondant out to 5mm thick. I placed it over the bottom cake and smoothed it over. I placed 4 straws into the centre of the larger cake to stop the top tier squashing the bottom layer. Straws are cheaper, but of course, you can use cake dowels. I placed the smaller tier onto my icing turntable and covered that in fondant too, then used a little leftover cream cheese frosting in the middle of the covered larger cake to stick the top tier on.
I cut out small circles of fondant and stuck them on with a little royal icing mixed with water.
Cake will keep covered in fondant, at room temperature, for up to 5 days. If just covered in cream cheese frosting, cake will keep wrapped up in the fridge for 4 days.