Steps
1. Prepare the walnut sweet shortcrust:
- Mix flour, powdered sugar, ground walnuts, and salt.
- Rub in cold butter until mixture resembles breadcrumbs.
- Add cold water gradually to form a dough.
- Wrap dough and chill for 30 minutes.
- Roll out dough to fit a small tart mold (~8 cm diameter), ensuring thickness to yield about 40g baked shell.
- Blind bake at 170°C (340°F) for 12-15 minutes until golden. Cool.
2. Prepare the pastry cream:
- Heat milk and half the sugar until warm.
- Whisk egg yolk, remaining sugar, and cornstarch until smooth.
- Slowly pour warm milk into yolk mixture, whisking constantly.
- Return mixture to low heat, stirring until thickened.
- Remove from heat, add vanilla, cover with plastic wrap, and cool.
3. Make coffee Chantilly cream:
- Whip heavy cream with powdered sugar and instant coffee until soft peaks form.
4. Prepare pitahaya gelée topping:
- Soften gelatin in cold water.
- Heat pitahaya pulp gently, dissolve gelatin in it.
- Allow to cool but not set.
5. Assemble the tart:
- Fill baked tart shell with a layer of pastry cream (~20g).
- Pipe or spread coffee Chantilly cream over pastry cream (~15g).
- Gently pour pitahaya gelée on top to cover surface thinly.
- Refrigerate 1 hour to set gelée and creams.
6. Garnish and finish:
- Sprinkle crushed walnuts evenly.
- Place mint leaves decoratively.
- Lightly dust the entire tart with powdered sugar.
7. Serve chilled. Total weight approx. 80g.