Banana Muffin with Cottage cheese filling

Ingredients (32×13 mold, height 8 cm):

Dough:
Butter - 100g
Sugar - 60g
Bananas - 3 units (400g)
Sour cream 20% fat - 70g
Eggs - 2 units
Flour - 240g
Baking powder - 1 tsp.
Salt - 1 tsp.

Filling:
Cottage cheese - 240g
Sugar - 30g
Corn starch - 1 tbsp.
Egg - 1 unit
Bake at 180 degrees for 40-45 minutes.