Scoop 3 1/2 tbsp ice cream and melt in microwave for about 25 seconds.
Combine all ingredients into an oversized mug.
Mix with a small whisk until smooth. Batter will be thick. Microwave for approximately 1 1/2 minutes until knife inserted in middle comes out clean. Top of cake may have a slightly wet/gooey texture, which is fine as long as the inside is cooked.