The Great British Bake Off had slice and bake cookies with intricate designs as the signature challenge for episode 2. Most contestants used a shortbread cookie, which is not our favorite, so we opted for chocolate chip cookies. The good news is that the cookies are not watermelon chocolate chip flavored; we just needed a design that justified having dark bits inside. A watermelon design met the requirement for dark seeds in the middle, but it probably does not classify as intricate.

You might expect a little math for calculating the ingredients for a half batch or double batch, but we just made a full batch. (FYI, a half batch would have been enough.) Knowing John, you have to expect that there was excessive engineering and math involved.

How could you ruin cookies with math and engineering?

Very easily, just read on.

John decided that the green rind would be 20% of the batter with 10% being light green and 10% being dark green. The white part of the rind, the pericarp, would be another 10% of the batter. The math comes in for calculating the thickness of the various layers to ensure it will look right. The volume of a cylinder is π*R²*L, and all layers should have the same Length.

We are assuming that the outer radius, R1, is 1 inch, so they will be 2″ wide cookies…

You do not care do you?

Uh, … no?

Fine. We will get on with the pictures.

Kate made the base batter without chocolate chips, and John did the coloring and assembly. As you will see below, Kate is better about taking pictures than John.

1. Separate the batter by weighing it. The batch was about 1000 grams, so 100 grams each for dark green, light green, and uncolored.

2. Add the food coloring and mix it in. You can see the uncolored 10% on the counter in front and the light and dark green 10% on the stove in the back.

3. Mix the chocolate chips into the pink portion. We used 75% of the required chocolate chips because the pink part is only 70% of the cookie batter volume.

4. Dump the pink batter onto wax or parchment paper, form it into a log about 2 inches wide and 14 inches long, and refrigerate the log.

5. Roll out the uncolored rind dough into a 14 inch long by 6 inch wide rectangle. Roll out each of the dark and light green rind dough into 14 inch long by 3 inch wide rectangles. Freeze all three of them.

6. Cut the light and dark green rind into strips, alternate the colors, roll the dough into a 6.5 inch by 14 inch rectangle, and freeze. (Note: This does not work very well with chocolate chip cookies dough. It might work better with more rind dough, or it might be better to alternate the dough before freezing. It would probably work better to use a thin flat piping tip and pipe the soft batter into stripes before refrigerating and freezing.)

7. Layer the white rind on the green rind, roll to ensure they are connected, and freeze.

8. Roll the rind around the log, apply pressure to make sure the layers are connected, and cut off the rough ends.

You can see the watermelon appearance on the ends of the log. You can also see that the cut is really rough. We found that a frozen log cuts cleaner.

9. Slice and bake some cookies in the toaster oven.

Hmmm … Maybe bake them a little less. Our second attempt at John’s sister’s house, using a real oven, worked better.

This batch looked good and tasted good. We think starting from a frozen cookie log and using a full sized oven both helped to make them turn out better.

In this process, mistakes were made, and lessons were learned…

• The chocolate chips change the volume of the pink batter, and this throws the size calculations off.
• Using 10% for each part of the rind was insufficient. Using 15% to 20% for each will probably work better.
• RV refrigerators do not get as cold as home refrigerators, so the refrigerated dough was hard to work with. Freezing worked better.
• Freezing the cookies log makes it slice better and cook better.
• This whole endeavor was a pain in the rear.

You should learn from our mistakes and just make normal cookies.