Line a 9 x 9 x 2-inch baking pan with nonstick foil. Trim browned edges from pound cake. Balance cake on one long side, and slice loaf lengthwise into 4 equal pieces (each about 9 x 3 1/2 x 1/2 inch).
Unwrap mints and place in food processor. Pulse to crush. Transfer crushed candies to a large bowl, chopping pieces that seem too large. Place cookies in food processor and pulse to make into coarse crumbs.
Place 2 cake slices in bottom of foil-lined pan, trimming length if needed. Add ice cream to mints in bowl. Working quickly, blend ice cream, crushed mints and mint extract until smooth. Spread half of the ice cream into pan, spreading all the way to pan edges and completely covering cake. Top with remaining 2 cake slices, and then remaining ice cream, spreading smooth. Sprinkle crushed cookies over ice cream, and gently press to adhere. Cover with a sheet of foil and freeze for 2 hours.
Remove cake from freezer and use foil to lift from pan to a cutting board. Working quickly, slice cake in half. Use a spatula to stack one half on top of second half. Use foil to transfer back to pan. Re-cover with foil and freeze overnight.
Microwave heavy cream for 1 to 2 minutes or until it just begins to bubble. Pour over chopped chocolate in small bowl. Let stand 5 minutes. Whisk until smooth.
Remove cake from freezer. Remove foil and invert cake onto a small cookie sheet lined with nonstick foil. Trim off any bumpy sides with a sharp knife. Pour chocolate mixture over cake in batches, using a large spatula to spread down the sides. Top with extra chopped cookies and candies, if desired. Return to freezer until serving (at least 2 hours). Transfer to serving platter before slicing.