Set aside a 9 by 5 by 3 inch metal loaf pan.
In a large mixing bowl, whisk together the sweetened condensed milk and the almond extract.
In the bowl of an electric mixer, beat the cream using the whip attachment until stiff peaks form.
Using a rubber spatula, place a dollop of whipped cream on top of the sweetened condensed milk mixture. Whisk the cream in.
Add the remaining cream on top of the lightened mixture and using a rubber spatula, fold quickly until well combined.
Place a quarter of the mixture into the loaf pan, and evenly distribute. Scatter a small handful of crumbled halvah followed by fresh raspberries and pistachios.
Using a butter knife dipped into green gel food coloring (if using), gently swirl the knife through the cream mixture randomly.
Repeat layering the remaining cream and toppings, and use the same knife (no need to dip again in food coloring) to make a few random swirls in each layer.
Wrap plastic wrap over the top of the semifreddo, making sure it is well covered, and pressing down gently. Freeze overnight.
Leave the semifreddo in the refrigerator for about 15-30 minutes to soften. Scoop and serve.