Butter Crumb Muffins

Ingredients

• flour - 7 oz (200 g)
• sugar - 5.3 oz (150 g)
• eggs - 1 XL
• yogurt - 4.6 oz (130 g)
• bananas - 1 large (well ripened)
• butter - 2.8 oz (80 g) at room temperature, very soft
• lemon juice - about 1 tbsp.
• baking powder - 1 tsp.
• bicarbonate of soda - 1 tsp.
• salt - 1 pinch
• flour - 1.1 oz (30 g)
• butter - 0.7 oz (20 g), cold
• sugar - 1.4 oz (40 g)
• cinnamon - 1 pinch, powdered