Marshmallow sandwiches

Ingredients

• 200 grams (7.05 ounces) butter 82.5%
• 1 egg
• 130 grams (4.60 ounces) powdered sugar
• 1 teaspoon baking powder
• pinch of salt
• 340 grams (12.00 ounces) flour
• 200 grams (7.05 ounces) blackcurrants
• 2 tablespoons sugar
• 1 tablespoon corn starch
• 260 grams (9.15 ounces) blackcurrants
• 180 grams (6.35 ounces) sugar (1)
• 50 grams (1.75 ounces) egg whites
• 140 grams (4.95 ounces) water
• 10 grams (0.35 ounces) agar
• 260 grams (9.15 ounces) sugar (2)
• 100 grams (3.55 ounces) glucose syrup