Banana sandwich cookies with chocolate icing

Ingredients:

Cookie

• 3/4 cup premium flour
• 0.5 cup granulated sugar
• 1/4 cup cocoa powder
• 1/4 teaspoon of baking soda
• 4 tbsp unsalted butter, melted
• 2 tbsp. milk
• 1 large egg yolk

Banana filling

• 4 tablespoons unsalted butter at room temperature
• 2 tbsp. confectionery fat
• 3/4 cup powdered sugar
• 0.5 tsp banana extract
• 1/4 tsp vanilla extract
• 1 firm ripe banana

Dark chocolate ganache

• 450 g dark chocolate chips
• 3 tsp. confectionery fat

Preparation:

1. Cookie:
   
   Sift the flour, granulated sugar, cocoa powder, and baking soda together in a medium bowl and set aside. In a separate bowl, beat the butter with the milk and egg yolk until smooth in texture and color. Add the butter mixture to the flour mixture and knead into a dough. Divide the dough in half and place each half on a piece of plastic wrap or parchment paper.
2. Form two logs, 2.5-3.5 cm in diameter. Refrigerate for at least 4 hours or overnight.
3. Preheat oven to 190°C. Line 2 baking sheets with parchment paper.
4. Remove one piece of dough from the refrigerator. Cut into 0.5 cm thick slices and place on a baking sheet. Bake until set, 9-10 minutes. Transfer to a wire rack to cool. Repeat with the second piece of dough.
5. Banana filling:
   
   Place the butter and shortening in a small bowl and beat with a mixer on medium speed until smooth, about 1.5 minutes. Reduce the mixer speed to low and add the powdered sugar in two additions. Add the banana and vanilla extracts and mix until fully incorporated; set aside.
6. Collect the cookies:
   
   Slice the banana into 36 0.3 cm thick slices. Spoon 0.5 teaspoon of filling onto each cookie. Place a banana slice on top of the filling, making sure it doesn't extend beyond the edges, then top with another cookie and press lightly.
7. Ganache:
   
   Pour a couple of centimeters of water into a saucepan and heat over medium-low heat, just above a boil. Place the chocolate and fat in a metal bowl and set it over the hot water. Stir until melted. If the water starts to boil too vigorously, remove the bowl from the saucepan to prevent the chocolate from burning. Once completely melted, remove the saucepan from the heat, leaving the bowl with the chocolate above the water.
8. Using two forks, dip the cookies into the melted chocolate, carefully flip them over to coat, and transfer them to waxed paper. Let them sit at room temperature until the chocolate is completely set, at least 2 hours.