In a large bowl mix butter, sugar, and vanilla. Then add eggs and salt and whisk until smooth.
Stir in the flour until just combined, then gently mix in sprinkles. Add batter into the 9x13 pan lined with foil.
Bake for 25-30 minutes then allow to cool completely.
In a bowl beat butter for 2 minutes until smooth.
Add vanilla, salt, powdered sugar, and half of the milk. Mix for a minute then add the rest of the milk and 2 drops food coloring. Mix and spread over cake. Garnish with sprinkles. Enjoy!