Bring sugar and 2 tablespoons water to a boil in a medium saucepan, stirring until sugar is dissolved. Continue to cook until a thermometer inserted in mixture registers 235 F degrees.

Add peanuts and stir until sugar begins to from white crystals and form a sandy coating. Stir in salt and cook, stirring, until the white crystals started to melt again and caramelize into golden brown and nuts darken slightly, about 3 minutes more. Pour onto a parchment-lined baking sheet and let cool completely before serving or storing at room temperature up to 1 week.

Preheat oven to 375 degrees. Coat a 9-by-13-inch baking pan with cooking spray. Line with parchment, leaving overhang on long sides; coat parchment with cooking spray. Whisk together flour, cocoa, salt, and baking powder in a bowl.

In a large bowl, beat butter with sugar on medium speed until pale and fluffy, about 3 minutes. Add eggs, one at a time, beating until smooth. Beat in vanilla. With mixer on low speed, add flour mixture in three batches, alternating with milk in two additions, beating until combined. Beat in melted chocolate.

Transfer batter to prepared pan, smoothing top with an offset spatula. Bake until set on top but still wobbly in center, about 15 minutes. Let cool completely in pan on a wire rack.

Line an 8 1/2-by-4 1/2-inch loaf pan with plastic wrap. Use parchment to lift brownie from baking pan. Cut crosswise into 3 pieces, one piece cut to fit bottom of loaf pan exactly, the next slightly wider, and the last widest of all (to match size of pan, which gets wider toward top).

Place smallest brownie piece, top-side up, in bottom of lined loaf pan. Spread the 1 1/2 cup of ice cream. Place second-largest brownie piece, top-side down, on ice cream. Spread with crushedraspberries, then the rest of the ice cream. Top with final brownie piece, topside down. Cover with plastic wrap and freeze until firm, at least 6 hours and up to 1 day.

Run a butter knife around edges to release lined cake from pan, then use plastic to remove cake and place on a serving platter. Top with whipped cream and sprinkle with sugared peanuts. Slice with a sharp knife, wiping blade clean between each. Serve each slice with more peanuts