Preheat oven to 400° F (200° C) Line a baking sheet with parchment paper.

In a bowl, sift together the flour, sugar and salt. Set aside.

In a heavy saucepan, combine butter and water over medium heat. Bring to a boil, making sure the butter fully melts before the water boils. Tip: I cut the butter into smaller pieces to have it melt faster.

Remove from heat and add the flour mixture into the saucepan and stir well. Return the pan on to medium heat and stir until the dough forms a smooth ball and pulls away from the sides of the pan, about 1–2 minutes.

Transfer dough to a mixing bowl. Beat for about 1 minute to release steam. Once the dough is warm (and not hot), add in one egg at a time; mix until smooth and then add in the next egg until the dough is smooth and glossy.

Transfer dough to a piping bag or large zip-top bag. Pipe 12–18 rounds onto the prepared baking sheet. Lightly tap the tops of the dough with a wet finger if there are any peaks to make sure it doesn’t brown or burn. Brush the dough with an egg wash.

Bake for 15 minutes at 400 and reduce the oven to 350° F (180° C). Bake for about another 25 minutes. Remove briefly, and poke a hole in the button of the puff to make sure the bottom dries. Put back in the oven for 10-15 minutes until lightly browned. Cool completely on a wire rack.

In a medium-sized bowl, whisk the milk, sugar, flour and cornstarch until smooth. Strain it through a sieve into a small saucepan to remove any lumps.

Cook over low heat, whisking constantly, until thickened and the custard slowly falls from the whisk. Add butter until combined and melted into the mixture.

Transfer to a bowl, cover tightly with plastic wrap touching the surface, and refrigerate until fully chilled, 1–2 hours.

In a large mixing bowl, combine all the whipping cream ingredients in the bowl. Whip the cream until stiff peaks form. Tip: All ingredients should be cold for the whip cream to get peaks.

Gently fold the chilled milk cream into the whipped cream until smooth and evenly combined.

Split the pastry shells in half and fill with injeolmi cream. Best if enjoyed within a few hours! You can store in fridge or freeze them for longer enjoyment!