In a heat-proof bowl, combine the raisins and the hot water. Allow to rest for 10-15 minutes. Drain the raisins and dry them off with paper towels or a tea towel.
240 grams water, 200 grams raisins
In a large mixing bowl, whisk together the flour, baking soda, salt, ground cinnamon and oats.
In another bowl, combine the melted butter and sugar. Whisk vigorously until the sugar is mostly dissolved. Allow to cool for 5 minutes if the butter is really hot.
225 grams butter, 220 grams light brown sugar, 100 grams white granulated sugar
Add in the eggs and vanilla. Whisk together until fully combined.
1 tablespoon vanilla extract, 2 eggs
Pour the wet ingredients into the dry ingredients. Add the raisins, and then mix until a soft cookie dough forms.
Line a plate or baking tray with baking paper/parchment paper. Then portion out the cookie dough in 2 tablespoon-sized balls. I used a 2 tablespoon cookie scoop. Place the cookie dough balls onto the baking tray with parchment paper. Cover with cling film. Alternatively, line an airtight container with baking paper and place the portioned cookie dough balls in the container.
Let the cookie dough balls rest in the fridge for at least 20 minutes up to 24 hours. I recommend 24 hours.
Preheat the oven to 180°/350°F. Line a baking tray or two with baking paper or parchment paper.
Place the chilled cookie dough balls on the baking tray about 2 to 3 inches apart. Bake for 15 to 20 minutes. My cookies were done at the 18-minute mark.
Let the cookies cool on the baking tray for at least 5 minutes before carefully lifting onto a wired rack to cool completely.
All temperatures stated are for conventional ovens. Decrease the temperature by 20°C/25°F or gas mark 1 for "fan" or air-fryers.
Notes
225 grams of butter is equal to two stick of butter, and is 25 grams less than a metric cup of butter.
Once you have soaked the raisins, drain them and then dry them between a few sheets of paper towel, or in a clean tea towel/kitchen towel. We want to remove as much of the excess water as possible.
The cookie dough may initially look a bit too soft, but as the dough stands the butter will become more solid, and the oats and flour will absorb the moisture in the cookie dough.
The cookie dough must rest for at least 20 minutes in the fridge, but the flavor is really great after a 24-hour chill in the fridge.
Reduced Sugar Variation (for a full batch)
25% reduction - 165 grams (¾ cup) of brown sugar, and 75 grams (⅓ cup)of white sugar.
50% reduction- 110 grams brown sugar (½), and 50 grams (¼) of white sugar.
Because of the sugar reduction, the cookies won't spread as much during baking. If you want a flatter cookie, then press down the cookie balls to about 1cm tall before chilling.
Storage and Freezing
Store the baked cookies, once completely cooled, in an airtight container for up to a week.Baked, cooled cookies can be frozen in an airtight container for up to 3 months.Portioned cookie dough balls can be stored in an airtight container for up to 3 months. To bake, preheat the oven and bake from frozen. You may need to add 2 to 3 minutes to the baking timing.