• In a mixer bowl, combine butter and both sugars. Mix on medium until you achieve a light and fluffy consistency, which should be around 4 minutes.
• Introduce eggs into this sugar mixture, ensuring the mixer speed is set to low, until well combined.
• In a separate spacious bowl, blend cake flour, all-purpose flour, quick oats, cornstarch, baking soda, salt, and cinnamon. Once mixed, gradually integrate this dry mix into your sugar mixture on low speed.
• Add the festive touch! Incorporate the white chocolate chips, holiday sprinkles, and M&M’s on low speed until evenly distributed.
• Cover your dough with plastic wrap and let it chill in the refrigerator for 15-20 minutes.
• Preheat your oven to a toasty 410 degrees Fahrenheit.
• Roll out your dough on a floured surface until it's about ½ inch thick.
• Using a medium circle cookie cutter, create 24 cookie circles. Arrange them on a parchment-lined baking tray.
• Bake for 10 minutes, or until they have a golden brown top.
• Give them a 5-minute break before placing them on wire racks to cool.

For the Vanilla Cream Icing:

• In a mixing bowl, combine butter, powdered sugar, and vanilla extract.
• Use a hand mixer to whip until the mixture is pale and fluffy.
• Fill a piping bag with a round tip with the vanilla icing.
• Flip half of the cookies over.
• Gently squeeze the vanilla icing onto the cookies.
• Top with another cookie to create the sandwich. Ensure the icing reaches the edges. Repeat for all the cookies.