Add butter and sugar to a mixing bowl and cream until light and fluffy, about five minutes.

Scrape the bowl down halfway through beating.

Add sour cream, eggs and vanilla and beat well until combined.

Add 3 cups of flour and baking soda and beat just until combined.

Add remaining 3 cups of flour and beat until just combined.

Cover and refrigerate for 30 minutes. 

Preheat oven to 375 and line a baking sheet with parchment paper. 

Sprinkle flour onto a flat surface and add a small amount of dough (a little bigger than tennis ball size) to the surface and use a rolling pin, also dusted in flour, to roll the dough into 1/4" thickness.

Use a 3" round cookie cutter to cut the dough into cookies and place onto the prepared baking sheet. 

Bake for 7-9 minutes or until bottoms are golden brown.

Remove from oven and let stand on baking sheet for 2 minutes before removing cookies from the baking sheet and placing them onto a cooling rack to cool completely.

Repeat until you have all of the dough rolled and cookies made. 

Add powdered sugar meringue powder and 5 tablespoons water to a heavy duty mixer fitted with a paddle attachment.

Beat on low speed until mixture forms a large ball.

Slowly add 1 additional tablespoon water and continue to beat for 7 minutes, mixture will be thick and probably like a ball.

Continue to add 1 tablespoon water and beat on low until you have the desired consistency. 

The best consistency for flooding icing is to dip your spatula into the bowl and let the icing drip into the bowl. If the icing completely sinks and blends in with the icing in the bowl within 10 seconds, it's ready to be flooded. 

Divide icing into 5, about 1/2 cup bowls. Cover each bowl with damp paper towel to prevent the icing from drying out.

Place one bowl of icing, white, into a pastry bag and twist the bag shut. Color remaining icing with color gels, and add to a pastry bag until you have 5 colors. 

Once cookies are completely cooled, make sure you are working on a flat surface and snip the tip of the icing bag open, to about 1/8". Start small and increase the opening if necessary. 

Beginning with the white icing, draw an oval off center to create the beach ball seam. Draw section lines on the cookie to create the color areas, making sure the icing is hovering over the cookie rather than touching the cookie.

Fill each area with white icing. Set the icing aside and cover the open tip of the pastry bag with a damp paper towel. 

Begin adding additional colors to the beach balls by filling in the blank spaces with the other icing. Use a toothpick to help fill the void areas when you pipe the icing onto the cookies.

Once all colors are added, return to the white icing, add a second layer on the oval of the beach ball so it's more dimensional and creates more of a 3D shape. 

Let stand until completely dry. This could take 1 or more hours depending on the humidity in the room.