- Grease slow cooker (4.5 to 6 L capacity) with cooking spray. In bowl, whisk flour with cocoa powder, baking powder and salt. Set aside.
- In a separate bowl, beat butter and sugar using electric mixer on medium speed about 2 min. until light and fluffy. Beat in egg. Beat in sweet potato and vanilla.
- With mixer on low speed, add the dry mixture to the sweet potato mixture in 3 parts, alternating with the milk in 2 parts, starting and ending with the dry mixture. Scrape bowl as needed between additions.
- Scrape batter into slow cooker; smoothing top. Cover and cook on LOW setting 1 hr 10 min (or 10 min. longer) until firm and edges are browned. Let stand 15 min. in slow cooker. Invert ceramic insert of slow cooker to remove cake; cool completely on wire rack.
- Meanwhile, make frosting by beating cream cheese with electric mixer until light and fluffy. Beat in butter completely. Then beat in icing sugar, vanilla and cardamom just until smooth.
- Place cake on serving plate. Spread frosting over top and sides. Store refrigerated in airtight container up to 2 days.
• To cook sweet potato, pierce sweet potato with fork and cook on HIGH in microwave for 8 to 10 min. or until tender. Cool slightly; peel and mash with fork until smooth.
• Layer leftover cake and cream cheese frosting with prepared chocolate pudding to make mini trifles or crumble leftover cake and serve over ice cream.