In a large bowl, combine the yellow cake, eggs, oil, and yogurt. Zest the limes and squeeze the lime juice into the cake batter. Stir to combine.
Place a large piece of parchment paper into a slow cooker. Pour the cake batter into the bottom. Cook on high for 1 1/2-2 hours, or until toothpick inserted into the center comes out clean.
Using the parchment paper, lift the cake out of the slow cooker and cool on a wire rack.
To make the glaze, combine the powdered sugar, lime juice, milk, butter, and zest. Add more milk, if needed.
Spread the glaze all over the cooled cake.
