Preheat your oven to 350 degrees.
Line a 13x9 glass baking dish or baking pan with parchment paper.
Set it to the side.
In a large bowl, add your melted butter, sugar, vanilla, and milk.
Mix until everything is well combined.
Add in the eggs one at a time, but one at a time.
Mix until the eggs are well incorporated.
In a separate large bowl, add the flour, baking powder, cream of tartar and salt.
Whisk the dry ingredients.
Add the wet ingredients to the dry ingredients.
Mix until well combined.
Pour the snickerdoodles batter into the 13x9 pan.
In a small bowl, add the 2 tbsp of sugar and 1½ teaspoons of cinnamon.
Mix ingredients.
Sprinkle the topping over the batter.
Bake for 25-28 minutes.
Once removed from the oven let it cool to room temperature.
Cut into bars.
Serve & enjoy!