Preheat oven to 350F. Spray two 8x4" loaf pans liberally with baking spray, such as Baker's Joy. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment (or in a large mixing bowl with an electric hand mixer), beat together cream cheese and eggs until incorporated. There may still be some small pieces of cream cheese not combined with the liquid--that's okay!
To this mixture, add the dry cake mix and vegetable oil. Mix on low speed for about 30 seconds, allowing the batter to start coming together. Scrape down the sides of the bowl, then turn the mixer to the medium-high setting and beat for about 2 minutes more. The batter should be smooth and creamy.
Add the red and green sprinkles to the batter, then use a spatula or spoon to gently fold them into the batter by hand. Stir the batter just until the sprinkles are incorporated.
Divide the batter between the two prepared loaf pans, smoothing out the tops. Bake in preheated oven for 35-40 minutes, or until a toothpick inserted in the center of the loaves comes out clean.
Remove from oven and let the loaves cool in the pans for about 10 minutes, then turn the loaves out onto a wire rack or serving plate to cool completely.
Once the loaves are completely cool, prepare the glaze. Combine powdered sugar, vanilla extract, 4 tablespoons of heavy cream (or milk), and a pinch or two of salt in a small mixing bowl. Whisk together until smooth. If needed, add more heavy cream to thin the glaze, or a bit more powdered sugar to thicken it.
Drizzle the glaze over the tops of the loaves, letting it run down the sides of the loaves a bit. Allow the icing to set up for about 10-15 minutes--it will harden to a satiny finish over that time. Then slice and serve!