Preheat oven to 350 degrees F. Liberally grease a 9-inch loaf pan with a little cold butter or gluten-free nonstick spray; set aside.
In the bowl of a stand mixer, beat together the butter and sugar until light and creamy. Add in the eggs, one at a time, mixing well after each addition. Beat in the vanilla bean paste/vanilla extract to combine.
In a medium bowl, sift together the White Rice Flour, Sorghum Flour, cornstarch and baking powder. Gradually add the flour mixture to the wet mix, beating well after each addition until a soft batter has formed. Spoon about ½ cup of the batter into a separate smaller bowl; stir in about ⅓ cup of Nutella to blend.
Spread the vanilla pound cake batter into the prepared pan in an even layer. Top with globs of the Nutella batter. Use a butter knife to gently swirl the Nutella batter into the vanilla pound cake batter, giving it a marbled effect. Place the pan in the oven and bake for 40-50 minutes or until a toothpick inserted near the center comes out mostly clean. Cool slightly before inverting the cake carefully onto a wire rack to cool completely.
Once cooled, use the remaining ¼ cup of Nutella to drizzle onto the pound cake -- I popped the remaining Nutella in the microwave for about 15 seconds to soften. Immediately sprinkle with rainbow sprinkles and serve! Store airtight, at room temperature, for several days.
Recipe by The Domestic Rebel at https://thedomesticrebel.com/?p=4608