In a medium bowl, stir together sweetened condensed milk, 1/4 cup of the salted caramel sauce, and vanilla extract. Set aside.: As you mix, notice the glossy sheen the sweetened condensed milk takes on when combined with the salted caramel sauce . The aroma will deepen, giving a rich, caramel note that hints at the finished dessert. Use a rubber spatula to scrape the bowl, ensuring there are no unmixed pockets. Why this matters, the base must be homogenous so the subsequent folding of whipped heavy cream creates even texture. Common mistake to avoid is over stirring so the mixture becomes too thin; a few gentle folds are enough. If the caramel looks separated, a brief, careful stir brings it together without deflating air you will add later.
In the bowl of a stand mixer, using the whisk attachment, beat cream on high until stiff peaks form, about 3 minutes. With a rubber spatula, gently fold whipped cream into the sweetened condensed milk mixture. Stir in pretzel pieces and chopped Heath candy bars.: As the cold heavy cream whips it will first lighten, then thicken, and finally hold peaks; you will hear a change in the mixer as it gains structure. Stiff peaks mean the cream will stand up when the whisk is lifted and it will resemble soft mountains with glossy tips. This aeration is the secret to no churn texture, trapping air that keeps the ice cream light once frozen. A typical error is whipping too little which leaves the base dense, or whipping too much which can turn grainy; stop as soon as stiff peaks appear. If the cream smells faintly sweet and buttery, you are on the right track.
Pour ice cream mixture into a loaf pan or container. With a knife, swirl the remaining salted caramel sauce into the ice cream. Smooth with a spatula and sprinkle additional pretzel pieces and candy bar pieces over the top, if using. Cover with plastic wrap and freeze until firm, about 6 hours.: Right after whipping, tilt the bowl and use a large rubber spatula to fold, scooping from the bottom up to preserve air. You should see ribbons of pale cream disappear into the glossy condensed milk blend, creating a billowy, unified mixture. The texture should be light yet substantial, with a smooth sheen. Why this step matters, aggressive stirring knocks out the air and ruins the texture, producing an icy or heavy final product. Avoid using a whisk or electric mixer here; that will deflate the whipped cream. If you see streaks of unincorporated cream large enough to notice when spooning, gently finish folding until uniform.
When ready to serve, remove from freezer and scoop!: As you fold in the chopped pretzels and Heath candy bars , pay attention to the distribution so every portion has crunch. The toffee will lend caramelized depth while the pretzels add savory sparks; together they create satisfying contrast. Work quickly but gently, folding until the mix shows an even scatter of bits. Why this matters, uneven distribution results in some scoops being all crunch while others are bare. A common misstep is overmixing which can grind the candy into very small fragments that will weep sweetness into the base, so stop when pieces are evenly dispersed.
Note - I like to use my homemade salted caramel sauce. Will keep covered in the freezer for 3-4 weeks.: Pouring the mixture, you will see its silky weight settle into the pan; use a spatula to level the surface so swirls are distinct. Drizzle the reserved salted caramel sauce in lines or dollops, then run a knife through a few times to create beautiful ribbons. The aroma of caramel will lift as the pan chills. Scatter the reserved chopped pretzels and toffee for a textured crown that stays crunchy. Cover tightly to prevent freezer burn, and allow a minimum of about 6 hours to firm; this resting time enables the structure to set evenly. One pitfall is burying the garnish too early which causes it to absorb moisture; add decorative pieces near the end or right before serving for maximum crunch.
When ready to serve remove from freezer and scoop: Removing the pan, let it sit at room temperature for a few minutes so scoops glide without tearing the ice cream. You will see the ribbons of salted caramel sauce gleam through the surface and the top bits should be crisp and inviting. Use a warm scoop or run the scoop under hot water then dry it for clean, pretty balls of ice cream. If the texture is icy or hard, that indicates insufficient whipping or not enough fat in the base, so return it to the freezer and allow more time. Serve in chilled bowls for the best presentation.
Note I like to use my homemade salted caramel sauce Will keep covered in the freezer for 3 to 4 weeks: This note is a reminder that a flavorful salted caramel sauce elevates the whole dish; a homemade sauce will often taste richer and less processed than store bought. The finished ice cream keeps well when wrapped and stored, but for peak flavor enjoy within 3 to 4 weeks. A common storage error is leaving it uncovered which causes freezer burn and an off taste; always press plastic wrap onto the surface before sealing the container.