Preparation

1. Heat the oat milk in a small saucepan until lightly simmering. Put the heated milk, corn syrup, ¼ cup of the brown sugar, salt, vanilla, xanthan gum, grapeseed oil, and peaches into a blender jar in the order listed. Blend until the mixture is smooth. Transfer to a small bowl, cover, and refrigerate at least 2 hours, preferably overnight.
2. Preheat the oven to 325°F. In a small bowl, combine the oats, flour, cinnamon, and remaining 1 tablespoon brown sugar. Add the butter. Using your fingers or a fork, mash the butter into the oat-flour mixture until there are no dry bits left and the mixture is crumbly. Spread the mixture on a sheet pan lined with parchment paper. Bake until golden-brown, about 20 minutes. Let the oat streusel cool completely, and then reserve.  
3. Turn on the Cuisinart® ice cream maker. Whisk the ice cream base, and then pour the mixture into the freezer bowl through the ingredient funnel. Churn until thickened, about 20 minutes. Gradually add 2 tablespoons of the oat streusel and the peach jam through the funnel a few minutes before the end of churning time. Note: only a couple of tablespoons will be needed for this recipe. The remainder can be stored in an airtight container in the freezer for up to two months. It can be used for more ice cream, or even stirred into yogurt or oatmeal.
4. The ice cream will have a soft, creamy texture. For a firmer consistency, transfer the ice cream to an airtight container and place in the freezer for about 2 hours. Remove from the freezer about 15 minutes before serving.