Prepare the sweet corn ice cream: Melt butter in a medium saucepan over medium. Stir in corn and water; cover and cook, stirring occasionally, until corn is very tender, about 15 minutes. Transfer mixture to a blender.
Add whole milk and sugar to blender; process until smooth. Pour through a fine wire-mesh strainer into a medium bowl; discard solids. Stir in sweetened condensed milk, evaporated milk, vanilla, and salt. Cover and chill 2 hours.
Pour mixture into freezer bowl of a 1 1/2-quart electric ice-cream maker, and proceed according to manufacturer's instructions. (Instructions and times will vary.) Transfer to a freezer-safe container, and freeze until firm, about 2 hours.
Prepare the taco shells: Whisk together flour, salt, and 3/4 cup of the powdered sugar in a medium bowl.
Beat egg whites and remaining 2 tablespoons powdered sugar in a large bowl with an electric mixer on medium-high speed until stiff peaks form. Fold flour mixture into egg white mixture until just blended. Fold in melted butter, vanilla extract, and almond extract, and stir until fully incorporated.
Preheat a pizzelle maker according to manufacturer's instructions. Spray pizzelle maker with cooking spray. Spoon 2 tablespoons taco batter into hot pizzelle maker, and cook until golden brown, 1 to 2 minutes. Fold into a taco shape over a taco mold (or fold over the spine of a book), and let cool completely, about 2 minutes. Repeat with remaining batter. Freeze taco shells 5 minutes. Store taco shells in an airtight container in the refrigerator.
Fill each chilled taco shell with 1/2 cup sweet corn ice cream, and freeze 1 hour.
Prepare the chocolate sauce: Combine semisweet chocolate and coconut oil in a medium microwave-safe bowl. Microwave on HIGH until very well combined, 1 to 2 minutes, stirring every 20 seconds.
Prepare the ancho-spiced peanuts: Stir together peanuts and ancho chile powder in a small bowl.
Remove filled taco shells from freezer, and dip in chocolate sauce. Sprinkle with peanuts, and freeze until shell hardens, 5 to 10 minutes. Serve immediately.