In a small saucepan, toast the cinnamon, ginger, nutmeg, allspice, clove and white pepper over medium heat until fragrant, 1 to 2 minutes. Stir in the cream and bring to a light simmer, then remove from the heat and let cool completely. Store in a sealable container and refrigerate overnight.
The next day, place the cream in a food processor with the confectioners' sugar and salt. Spin the mixture until the fat turns into butter and the liquid separates. Transfer the mixture to a large piece of cheesecloth and wring out any excess liquid.
Transfer the butter to a small condiment bowl and use immediately or store in the refrigerator for later.