Sticky banana & maple cake

INGREDIENTS

• 100g softened butter , plus extra for the tin
• 8 tbsp maple syrup , plus extra to serve
• 3 small ripe bananas and 1 over-ripe banana
• 200g light muscovado sugar
• 4 eggs
• 2 tsp vanilla paste or seeds scraped from 2 vanilla pods
• 200g self-raising flour
• 100g ground almonds
• 1 tsp bicarbonate of soda
• 200g pot Greek yogurt