1. Preheat and Prepare

• Preheat your oven to 350°F (175°C).
• Line baking sheets with parchment paper or silicone baking mats.

2. Cream the Fats and Sugars

• In a large bowl, cream together 1/2 cup softened butter and 1/2 cup shortening until light and fluffy.
• Add 1 1/2 cups granulated sugar and 1 tablespoon brown sugar, and beat until combined.

3. Incorporate Eggs and Vanilla

• Beat in 2 large eggs, one at a time, ensuring each is fully incorporated.
• Add 1 teaspoon vanilla extract and mix until combined.

4. Combine Dry Ingredients

• In a separate bowl, whisk together 2 3/4 cups all-purpose flour, 2 teaspoons cream of tartar, and 1 teaspoon baking soda.

5. Mix Dry Ingredients into Wet

• Gradually add the dry ingredients to the wet mixture, mixing until just combined.

6. Add Sprinkles

• Gently fold in 5 to 10 ounces of nonpareils or jimmies, being careful not to overmix to prevent bleeding of colors.

7. Shape and Bake

• Using a cookie scoop, drop dough onto prepared baking sheets.
• Bake for 9-11 minutes, or until edges are lightly golden.

8. Cool and Serve

• Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.