Preheat oven to 180°C (Gas mark 4/350°F). Grease and line a 30cm x 20cm (12in x 18in) rectangle cake tin and place 4 muffin cases in a muffin tin.
Place the butter and caster sugar in a large bowl and whisk together until well combined and fluffy.
Add the eggs, two at a time, whisking after you add each pair. Once the eggs have all been whisked in, add the flour, vanilla extract and milk. Whisk again until fully combined.
Place a large spoonful of cake mixture into each of the 4 muffin case and smooth over the tops with the back of a spoon.
Pour the remaining cake mixture into the prepared cake tin. Gently smooth the top down with a spatula, then bake in the pre-heated oven - the cupcakes for around 25 minutes and the large cake for around 35 minutes, until golden and springy to the touch
Once the cakes are cooked, transfer to a wire rack and leave to cool completely before icing.
Whilst the cakes are cooling, prepare the buttercream icing. Whisk the butter until soft and fluffy. Add the icing sugar, a little at a time, whisking as you go until completely combined. Add the vanilla extract and whisk again until combined. Add milk, 1 Tbsp at a time, until the icing is at the correct consistency for spreading.
Draw the outline of a gummy bear shape on a piece of A4 paper and cut around it to use as a template for your cake. To make it easier, you can print one off - you'll find a link to the gummy bear template I used in the blog post.
Place your bear template on the rectangle cake and use a sharp knife to cut around it to create the base of your bear shaped cake.
Spread a layer of buttercream all over your bear shaped cake. Remove the cupcakes from their cases and slice off any rounded tops. Cover them in buttercream and place them, cut side down, on the cake for the bear's legs and arms.
Cut a round circle from one of the off-cut pieces for the bear's nose. Cover it in buttercream and pop it in place on the cake.
Once the cake is covered in the buttercream coating, pop it in the fridge or somewhere cool to allow the icing to set a little.
Roll the fondant out into a thin sheet that is big enough to cover the cake.
Carefully pick the sheet of fondant up (you'll find this easiest to do by rolling it carefully over your rolling pin), then starting at head end, carefully drape it over the cake, allowing the fondant to fall naturally to fill in the gaps between the nose and feet.
Gently smooth the fondant in place over the cake. Shape the fondant over any tricky shaped areas by gently pulling it away from the cake and smoothing it down around it - see my video to get an idea of the technique. Smooth the tops of the feet/nose and the sides of the cake, but don't press down too hard between them as the fondant will fall naturally and create a nice curved shape between them.
Once the fondant is moulded to the cake, cut around the edges to remove any excess and tuck the ends under the cake.
Gently press your thumbs into the ears to define the ear shapes and use a blunted cocktail stick to poke two small eye holes.