Preheat and prepare your tin. Set your oven to 180°C (fan 160°C). Grease a 20cm square baking tin and line it with a strip of parchment paper, leaving the ends hanging over the edges. This creates a handy sling to lift the cake out later.

Whisk the dry ingredients together. In a large bowl, sift together the flour, baking powder, bicarbonate of soda, cinnamon, nutmeg, ginger, and salt. The airy, pale brown mixture should smell deeply aromatic and look perfectly combined.

Add the wet ingredients. Add the light brown sugar, caster sugar, eggs, sunflower oil, and vanilla extract directly into the bowl with the flour mixture. Stir with a wooden spoon or spatula until just combined. You'll see a thick, glossy batter form—don't overmix, or the cake will be tough.

Fold in the carrots and nuts. Tip in the grated carrots and walnuts (if using). Fold gently until they are evenly distributed. The batter will look speckled with orange and will feel heavy and substantial in the spoon.

Bake until golden and springy. Pour the batter into the prepared tin and spread it level. Bake for 30–35 minutes, or until the top is a deep golden brown and a skewer inserted into the centre comes out clean. The kitchen will smell like autumn, and the cake will feel firm but spring back when pressed lightly.

Cool completely before icing. Leave the cake in the tin for 10 minutes, then lift it out using the parchment sling and transfer to a wire rack. Let it cool completely—this is crucial. If the cake is even slightly warm, the frosting will melt into a puddle.

Make the cream cheese frosting. In a medium bowl, beat 200g full-fat cream cheese with 50g unsalted butter (both at room temperature) until smooth. Add 250g icing sugar, sifted, and a splash of vanilla extract. Beat until thick, silky, and spreadable. Taste a little—it should be tangy, sweet, and utterly moreish.

Frost and serve. Spread the frosting evenly over the cooled cake. If you're feeling fancy, drag a fork through the top to create swirls. Slice into squares and serve. The first cut will reveal a moist, tender crumb flecked with carrot.