Pre-heat oven to 350 degrees and spray the outside of the cookie bowl tin with oil.
Whisk together flour and salt in a medium bowl.
In the bowl of an electric stand mixer, beat butter and sugar together until light and fluffy. Mix in egg and vanilla until fully combined.
Slowly add flour mixture, one cup at a time, mixing after each addition until just incorporated. Fold in sprinkles.
On a lightly floured surface, roll dough out to ⅛ inch thickness. Cut out 4 ½ inch circles (using a cookie cutter, biscuit cutter, or top of a drinking glass). You should be able to get 12 rounds.
Once dough circles are cut out, drape one circle over each bowl cavity of pan, pressing to form smooth surface. Place pan in the fridge for about 15 minutes.
Remove from fridge and bake for 11-13 minutes, until the cookies are beginning to turn golden brown. Cool them on the pan for 10 minutes and then remove them with a small spatula or a little bit of jiggling. Let cool completely on a wire rack.