Cream butter and sugar together. Add vanilla, milk, and flour. Mix until combined.
Place dough in between two pieces of wax paper.
With a rolling pin, roll dough to ¼ inch thick.
Peel top piece of wax paper off. Refrigerate for 30 minutes.
Using a 1-inch round cookie cutter, cut 48 circles out of dough.
Refrigerate for 15 minutes.
Prepare mini cupcake pan with mini cupcake liners.
Melt white chocolate chips. Coat the bottom of each mini cupcake liner with white chocolate. Shake pan to level it out.
Place 2 circles of dough in each liner.
Using remaining melted white chocolate chips, cover each sugar cookie circle. Shake pan again to lever it out.
Top each off with sprinkles of your choice.
Refrigerate until bark is hardened.