Let the eggs stand at room temperature for 30 minutes. This helps ensure the filling will blend smoothly.

Preheat your oven to 350°F (175°C).

In a mixing bowl, whisk together eggs, sugar, lemon juice, and orange zest until well combined. Gradually whisk in the melted butter until the mixture is smooth and glossy.

For the crust: In a food processor, pulse together the flour, confectioners' sugar, ground almonds, grated lemon zest, and grated orange zest. Add the cold cubed butter and pulse until the mixture forms a crumbly dough. Continue pulsing just until it comes together in a ball.

Press the dough evenly into the bottom and up the sides of a 9-inch fluted tart pan with a removable bottom. Use your fingers or the back of a spoon to smooth it out.

Pour the prepared lemon mixture into the crust. Spread evenly.

Bake the tart in the preheated oven for 25-30 minutes, or until the center is almost set and the edges are lightly golden.

Remove the tart from the oven and cool completely on a wire rack. Once cooled, refrigerate for at least 1 hour before serving.

Before serving, sprinkle with confectioners' sugar and top with fresh raspberries if desired.