In a small saucepan over medium heat, stir together 1 1/2 cups (ignore the quantity below - it's a technical issue I can't fix) of the coconut milk with the sugar and salt. Stir occasionally until the sugar is dissolved.
2 1/2 cups (591 ml) full-fat coconut milk, 7 tablespoons (88 grams) raw sugar, pinch salt
Meanwhile, mix the remaining 1 cup of coconut milk (ignore the quantity below - it's a technical issue I can't fix) with the cornstarch in a small bowl until well combined. It may appear lumpy at first but keep stirring and it'll combine.
2 1/2 cups (591 ml) full-fat coconut milk, 7 tablespoons (55 grams) cornstarch
Remove the pan from the heat and stir in the cornstarch mixture while stirring constantly. Once well combined, put it back on the stove, turn the heat to medium and cook until thickened like pudding, whisking constantly (do not walk away and do not stop whisking!). This will take anywhere from 30-60 seconds (some commenters have needed up to 3-4 minutes). Do not let it continue cooking once it's thickened - this can cause the cornstarch to break down and will make the pudding runny.
Remove from the heat and stir in the vanilla and coconut oil.
1 teaspoon vanilla extract, 1 1/2 teaspoons coconut oil
Let cool until room temperature and then pour into the chilled crust. Chill for about 1 hour before topping with raspberries.