Preheat the oven to 300°F. Line 2 baking sheets with parchment paper or silicone baking mats.
In a large bowl, toss the pumpkin seeds, almond and sunflower seeds and the syrup until evenly coated. Spread the nuts and seeds out, in an even single layer, on the lined baking sheets and season with salt to taste. Bake the nuts and seeds, stirring several times with a spatula or wooden spoon, until just golden, about 20 minutes.
Cool the nuts completely on the pan, then add the Mariani Cranberries and toss to combine. Store cooled trail mix in an airtight container at room temperature.