Preheat oven to 325°F (165°C).

Butter a 9-inch diameter glass pie dish.

Mix finely crushed amaretti cookies and melted butter in a medium bowl until evenly moistened.

Press the crumb mixture onto the bottom and up the sides of the prepared pie dish.

Bake until the crust is firm and crisp to the touch, about 10 minutes.

Cool the crust completely.

Line a baking sheet with foil and lightly oil it.

Stir sugar in a heavy medium skillet over medium-low heat until it begins to melt, about 8 minutes.

Increase heat to medium-high and cook until the sugar turns into a deep golden syrup, stirring occasionally, about 4 minutes.

Stir in the blanched slivered almonds.

Immediately pour the praline onto the foil-lined baking sheet and spread with a wooden spoon.

Let the praline stand until cool and firm, about 30 minutes.

Cut the praline into 1/2-inch pieces.

Transfer half of the praline pieces to a food processor and grind until a powder forms.

Reserve the remaining praline pieces for topping.

Spread 1 pint of slightly softened pistachio ice cream gently and evenly in the cooled crust.

Sprinkle 1/4 cup of praline powder over the pistachio ice cream.

Spread the slightly softened raspberry gelato evenly over the praline powder.

Sprinkle the remaining praline powder over the raspberry gelato.

Leaving a 1-inch border of raspberry gelato showing, spread the remaining slightly softened pistachio ice cream over the top of the pie, mounding slightly in the center.

Sprinkle the reserved praline pieces over the top.

Freeze the pie until firm, at least 4 hours.

Let the pie soften slightly at room temperature for about 5 minutes before serving.

Serve the pie with Raspberry Sauce, if desired.