Easter speckled egg cake

For the sponge:

225g butter

225g caster sugar

4 eggs

225g plain flour 

1 tsp baking powder

1 tsp vanilla extract

2 tbsp milk (optional)

For the butterscotch buttercream:

225g butter

450g icing sugar 

50g ocoa powder

1 tsp vanilla extract

2 tbsp hot water

3 tbsp Butterscotch Sauce

150g dark chocolate Vermicelli sprinkles

200g speckled chocolate candy eggs

chocolate caraque

fluffy yellow chicks

For the butterscotch sauce:

110g butter

175g dark soft brown, Muscovado sugar

225ml cream

½ tsp pure vanilla extract

Equipment:

2 x 20cm (8 inch) round sandwich tins