A swirl of blueberry sauce in creamy, full-fat labneh or Greek yogurt (these thickened yogurts are key here; less water), makes the sweet-tart flavor of these frozen bars. For the crust, substitute any ground nut you like. The ice cream maker is optional, but the texture of the finished bars will be icier than if the labneh base is churned. Corn syrup is very useful in creating a creamy texture.
Heat the oven to 325 degrees. Line an 8x8 pan with a parchment sling, with parchment overhang.
In a small bowl, combine the ground pistachios and the olive oil. Spread over the parchment=-lined bottom of the pan. A small offset knife helps here.
Bake the crust for 8 minutes. Cool completely.
In a small saucepan, combine the blueberries, lime juice, and sugar over medium heat. Break up the blueberries with a potato masher, and stir until simmering. If the blueberries aren't mashed, they will be icy when frozen.
Stir in the corn starch and continue to simmer, stirring constantly, until thickened. Cool completely. Placing the pot in an ice bath with speed the cooling process up if needed.
Whisk the labneh, cream cheese, corn syrup, sugar, salt, and lime zest until smooth.
If using, churn the labneh mixture in an ice cream maker according the manufacturer's instructions, until frozen like soft-serve.
Transfer the frozen labneh (or the whisked labneh if you didn't run it through an ice cream maker) and the blueberry swirl to a medium bowl. Gently fold the two together, leaving streaks of labneh (some will be more like lumps if the labneh was churned; this is fine).
Pour the labneh-blueberry swirl over the pistachio crust. Freeze for at least 3 hours and up to one week. Cut into squares and serve immediately.