Line the slow cooker with parchment paper, extending it up the sides for easy removal.
In a large bowl, whisk together almond flour, cocoa powder, sweetener, baking powder, and salt until well combined.
In a separate bowl, beat eggs, almond milk, melted coconut oil, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and stir until just combined, then gently fold in the drained cherries.
Pour the batter into the prepared slow cooker, cover with a clean kitchen towel under the lid to absorb condensation, and cook on low for 3 hours until the cake is set and a toothpick inserted in the center comes out mostly clean.
Allow to cool for 15 minutes before lifting out using the parchment paper, then slice and serve warm or at room temperature.