Line a 12-cup muffin pan with paper liners. Heat orange juice just to a simmer on the stovetop or in the microwave. Add raisins or currants and remove from heat. Set aside.
In a mixing bowl with an electric mixer, beat the sugar with the vegetable oil, eggs, vanilla, and orange zest until well blended.
Combine the flour, baking powder, soda, salt, and spices in a separate bowl and blend with a spoon or whisk. Add the flour mixture to the first mixture and stir just until all of the ingredients are moistened.
Drain the currants or raisins and fold them into the batter with the chopped walnuts and grated carrots.
Fill muffin cups about two-thirds full; bake in the preheated oven for 18 to 23 minutes, or until a toothpick comes out clean when inserted into the center of a muffin.
Notes
These moist carrot muffins are filled with raisins and chopped walnuts. Serve them with cream cheese spread or butter.