Whisk the coconut cream, oat milk, sugar, cocoa powder, corn syrup, cornstarch, and sea salt in a saucepan until smooth.
Cook the base over medium heat for 5 to 7 minutes, whisking constantly, until lightly thickened. Remove it from the heat and stir in the dark chocolate and vanilla extract.
Refrigerate the chocolate base for at least 4 hours, until completely cold.
Stir the peanut butter, powdered sugar, oat milk, and sea salt together until smooth and pourable.
Churn the cold chocolate base in an ice cream maker until thick and creamy.
Layer the churned ice cream with peanut butter swirl, crushed pretzels, and chocolate chips in a freezer-safe container.
Drag a spoon through the layers to create ribbons, cover the surface with parchment paper, and freeze for 4 hours.