Make the vanilla-maple syrup: combine the water and maple syrup in a small saucepan and bring to a gentle simmer over medium heat. Let it bubble lightly for 3–4 minutes until the mixture begins to thicken a little.
Remove the pan from heat. Split the vanilla bean lengthwise and scrape the seeds into the hot syrup, then toss in the scraped pod. Cover the pan and let the mixture steep for 15 minutes to extract maximum flavor.
After steeping, fish out the vanilla pod and stir in the pinch of sea salt. Pour the syrup through a fine mesh strainer into a clean jar and let cool to room temperature, then refrigerate. Syrup will keep up to 3 months chilled.
Prepare the sweet cream: in a blender or a large mason jar combine the almond milk, heavy cream and 1/4 cup of the cooled vanilla-maple syrup. Blend on medium-high for 20–30 seconds until the mixture is light and slightly thickened; if using a jar, shake vigorously for about 30 seconds or froth with a handheld frother.
Assemble the drinks: fill four tall glasses with ice and add 1 cup cold brew to each. Spoon or pour the vanilla sweet cream over the top — about 2 to 3 tablespoons per glass to start — then gently stir to combine or let it swirl for a pretty layered look.
Taste and adjust: if you prefer sweeter coffee, stir in an extra teaspoon or two of the vanilla-maple syrup into each glass. Serve immediately and store any leftover sweet cream in the refrigerator for up to 48 hours.