Prepare the brown sugar syrup by combining sugar and water in a small saucepan. Bring the mixture to a boil, stirring occasionally until all the sugar is dissolved. Reduce the heat and simmer for 10 minutes. Remove from heat and stir in vanilla. Allow the mixture to cool down.
In a large measuring cup or mixing bowl, combine the cream and the milk. Using a whisk or an electric whisk, whip the mixture until it forms medium peaks. Add the pumpkin puree, brown sugar syrup, and pumpkin spice and fold into the cream.
Fill a tall glass with ice and add cold brew coffee and brown sugar syrup, stir. Gently pour the pumpkin cream over the coffee and sprinkle a dash of pumpkin spice. Enjoy!
Store the leftover brown sugar syrup in an airtight container in the refrigerator up to 2 weeks. Use the syrup to sweeten other coffee beverages or iced tea.