No need to preheat the oven just yet, the dough needs to chill for an hour.
Place the butter and sugars into a large bowl, or the bowl of your stand mixer and beat until light and fluffy. Around 2 minutes on medium-high speed.
Add in the pumpkin and vanilla extract, scraping down the sides as necessary and mix until well incorporated, around 1 minute on medium speed.
Place the flour, salt, bicarbonate of soda, cream of tartar, spices and milk chocolate into a medium sized bowl and stir until the milk chocolate chips are coated in flour.
Tip the flour into the butter mixture and mix on low speed until the dough comes together into one big lump.
Tip the dough into the bowl you measured the flour into and place in the fridge for 1 hour to chill.
Once chilled, preheat the oven to 180C/350F and line two baking trays with silicone liners/grease proof paper.
Place the granulated sugar and cinnamon into a small, shallow bowl and stir until combined.
Take a 1.5tbsp cookie scoop and scoop a ball of dough. Roll the dough ball in the cinnamon sugar and then place on the baking tray. Leave a 2 inch gap between each cookie. Repeat the rolling into the sugar until you have exhausted your supplies. This will make about 18 cookies.
Place in the oven for 9-11 minutes, until ever so slightly coloured around the edges, soft in the middle and they look matte in the oven light.
Leave cookies to cool completely on the baking trays before storing, at room temperature, in an airtight container.
Pumpkin Chocolate Chip Snickerdoodles will keep for 1 week at room temperature.