Place the cake mix in a medium bowl.
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Add sour cream, eggs, and vegetable oil.
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Add Guinness.
3
Spray a slow cooker with baking spray and add the batter.
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Cook on low for 2 to 2 1/2 hours.
6
(Optional): Place heavy cream in a medium bowl.
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Beat with a hand mixer until cream begins to thicken.
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Add sugar and Guinness, then continue to beat until cream is thickened.
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