Stir together sweetened condensed milk and vanilla extract.: Listen for the quiet swirl and watch as the two ingredients combine into a glossy, thick pourable syrup. The scent should be sweet and milky with a gentle vanilla aroma, which signals the base is well blended. This step matters because it creates an even sweetness and flavor throughout the ice cream, preventing pockets of unmixed sugar. A common mistake is not scraping the sides of the bowl, leaving lumps of condensed milk. Use a rubber spatula to fold and scrape down the sides until everything is uniform in color and texture.
If using Cool Whip: simply fold the whipped topping into the sweetened condensed milk mixture.: simply fold the whipped topping into the sweetened condensed milk mixture. : When folding in Cool Whip , move gently in wide motions so you preserve the airy texture. Visually you want streaks of white to disappear into a pale, airy custard, with no streaks remaining. The lightness from the topping is what gives the ice cream its scoopable airiness without churning. Overmixing is a common pitfall, which will deflate the air and make the final product dense, so fold until just combined and stop.
If using heavy whipping cream: beat the cream until stiff peaks form, then fold into the sweetened condensed milk mixture.: beat the cream until stiff peaks form, then fold into the sweetened condensed milk mixture. : You should hear a soft whipping sound and see glossy peaks when you lift the whisk, peaks that hold their shape but are not grainy. This technique traps air, creating a light, silky mouthfeel in the frozen dessert. Chill your bowl and beaters for a crisper whip and start slow, increasing speed; this prevents splatter. Overbeating will turn the cream buttery, which ruins the texture, so watch carefully and test frequently.
Coarsely chop the almonds, then stir them into the ice cream. Warm up the hot fudge topping so that it’s pourable but not so hot it will melt the ice cream mixture. Drizzle it over the mixture and then gently stir it in to create a swirl. Don’t stir too much unless you want chocolate ice cream.: The almonds should be chunky enough to give distinct crunch, and toasting them briefly will release a nutty aroma that enhances the finished ice cream. Warm the hot fudge ice cream topping until it is glossy and pourable, about a few seconds in the microwave, then let it cool slightly so it does not melt the base on contact. Visually, you want dark chocolate ribbons threading through the pale cream, not fully blended. If you stir too vigorously you will lose the beautiful swirl effect and end up with uniform chocolate throughout, which is still tasty but different in character. A common misstep is pouring piping hot fudge, which can make the mixture too loose; aim for warm, not hot.
Pour into a plastic container and fit tightly with lid. Freeze for at least 4 hours or overnight. Keeps for 1 month in the freezer.: When transferring the mixture, tap the container lightly against the counter to release air bubbles and use a spatula to level the surface, which helps the texture set evenly. The aroma will settle into a sweet, nutty chocolate perfume as it chills. Freezing slowly preserves the silkiness, and letting it overnight ensures the ripple pockets set. Avoid opening the container repeatedly during the first hours of freezing, as temperature fluctuations can cause ice crystals to form, making the texture grainy. For easiest scooping, let the container sit at room temperature for a few minutes before serving so the edges soften slightly.
