Preheat the oven to 190°C (170°C fan) / 375°F / Gas Mark 5. Grease two 7-inch cake tins and line the bases with parchment paper.
Beat the butter and sugar together for about 5 minutes until pale, fluffy and almost doubled in volume. Don't rush this bit, it's what gives the sponge its lift.
Add the eggs one at a time, beating well after each, adding a spoonful of the flour with each egg to stop the mixture curdling.
Sift in the remaining flour, baking powder and salt. Fold in gently with a metal spoon, keeping as much air in as you can. Overmixing here makes for a dense cake.
Fold through the milk and vanilla until you've got a dropping consistency.
Divide the batter evenly between the two tins and bake for 25–30 minutes, until golden, springing back to a light touch, and a skewer comes out clean.
Cool in the tins for 10 minutes, then turn out onto a wire rack and leave to cool completely before decorating.
For the buttercream, beat the butter alone for 2 minutes until pale and fluffy. Gradually beat in the icing sugar, then add the vanilla and milk and beat for 3–5 minutes until light and spreadable.
Knead the brown modelling icing until soft and pliable. Roll into a sausage about 1cm thick and cut into four pieces. Shape each into a stumpy little leg with a rounded foot. Keep them a good 1cm thick or they won't hold their shape.
Trim the cake layers level if needed. Place one layer on your serving plate, spread with buttercream and then strawberry jam, leaving a 1cm border. Top with the second layer.
Spread a thin crumb coat of buttercream over the whole cake and chill for 15–20 minutes, then cover with a final, slightly textured layer.
Halve the strawberries and arrange in a ring on top, cut side down, with the candle in the centre.
Press the fondant legs onto the sides of the bottom layer, spaced evenly around the cake.
Using the black tube icing, pipe two dots for eyes and a simple curved smile.
Chill for 30 minutes if you want the buttercream to firm up, or serve straight away.