MELT butter and chocolate in saucepan on medium heat, stirring frequently. Remove from heat.
BEAT sugar, eggs, corn syrup and vanilla in 6-qt. bowl of mixer fitted with paddle attachment 3 min. Add chocolate mixture; mix well.
SIFT together flour, cocoa, baking powder and salt. Add to chocolate mixture; mix well, scraping sides of bowl occasionally. Pour into parchment paper-lined full-sheet pan (or into lined half-sheet pan for trial recipe).
BAKE in 350ºF standard oven 20 to 25 min. or until top is firm to the touch. Cool completely. Meanwhile, prepare Cheesecake batter.
BEAT cream cheese in 6-qt. bowl of mixer fitted with paddle attachment until creamy. Add sugar; mix until smooth. Add whole eggs and yolks, 1 at a time, beating on low speed after each just until blended. Blend in heavy cream and vanilla. Refrigerate until ready to use.
POUR 5 lb. cheesecake mixture (2.5 lb. batter for trial recipe) over cooled brownie layer in pan. Bake 22 to 28 min. or until cheesecake topping is almost set in center. Cool completely.
BROWNIE Pops: Cut brownie in full sheet pan into 6x4 pieces (2-1/2-inch rounds) to make 48 rounds (or cut into 6x4 pieces [2-1/2-inch rounds] to make 24 rounds for trial recipe). Place in single layer in separate parchment paper-lined full-sheet pan (or in separate lined half-sheet pan for trial recipe). Insert wooden pop stick halfway into side of thickest side of each brownie, keeping the stick as level as possible. Refrigerate or freeze until ready to dip in melted chocolate.
MELT chocolate in saucepan on low heat, stirring frequently.
DIP top 2/3 of each pop, 1 at a time, in melted chocolate. Slowly pull pop from melted chocolate, gently shaking as you pull the pop to remove excess chocolate from the pop. Return pops to prepared sheet pan. (Note: You can also gently scrape top of each pop before placing on the prepared baking sheet to remove excess chocolate.) Sprinkle each with 1 Tbsp. nuts. Let stand or refrigerate until chocolate coating is firm. Wrap individually in plastic wrap. Refrigerate up to 24 hours