Spray the inside of your slow cooker with non-stick cooking spray.
Add the arborio rice, almond milk, sugar-free sweetener, vanilla extract, cinnamon, and salt to the slow cooker and stir well to combine.
Cover and cook on low for 3 hours, stirring once halfway through if possible, until the rice is tender and the mixture has thickened.
Stir in the heavy cream during the last 15 minutes of cooking.
Turn off the slow cooker and let the pudding sit for 10 minutes to thicken further before serving warm or chilling in the refrigerator for later.