Preheat the oven to 180 °C.

In a saucepan, combine the water, 150 ml milk, 100 g butter, salt, and 1 tablespoon sugar, bringing it to a boil.

Remove from heat and add 150 g flour, stirring vigorously until well combined.

Return to medium heat, cooking the dough for about 2 minutes to dry it out.

Remove from heat and incorporate the 4 eggs one by one until fully mixed.

Transfer the pastry dough into a piping bag and shape a ring on a baking sheet lined with parchment paper.

Sprinkle with flaked almonds and bake for 30-35 minutes until golden brown and dry.

Allow it to cool.

Heat the remaining 500 ml milk until boiling.

In a bowl, whisk together the egg yolks, 100 g sugar, and cornstarch until pale.

Gradually whisk in the hot milk, then return the mixture to low heat to thicken.

Once thick, stir in 75 g of softened butter and cover with plastic wrap to cool.

Once cooled, combine the remaining butter and praline paste into the filling and fill another piping bag with this mixture.

Melt 100 g sugar in a pan over low heat until it turns golden caramel.

Stir in the whole almonds and hazelnuts, then spread them onto parchment paper to cool.

Once cooled, chop into pieces.

Carefully slice the baked pastry in half horizontally.

Fill the bottom half with the praline cream and sprinkle with crunchy praline pieces.

Place the top half back on and dust with icing sugar.