Cinnamon teacake with rhubarb - Moje wypieki

Ingredients

• 60 g butter
• 150 g caster sugar
• 1 tsp vanilla extract
• 1 large egg
• 150 g plain flour
• 1 tsp baking powder
• 80 ml milk
• 250 g rhubarb, sliced (no need to peel)
• 10 g butter, melted
• 1 Tbsp caster sugar
• 1 tsp ground cinnamon