Prepare the Pecan Pralines: Line a sheet pan with wax paper. Cook cream, cane sugar, brown sugar, and salt in a pot until it reaches 240°F. Stir in butter, vanilla, and pecans. Spoon onto the prepared pan to form 6-8 pralines.
Prepare the Semifreddo Pan: Line a 9x5x3-inch loaf pan with plastic wrap, leaving an overhang. Sprinkle the bottom with crumbled pecan pralines and chocolate-covered espresso beans.
Make the Custard: Mix egg yolks, cooled coffee, cane sugar, and salt in a glass bowl. Place over simmering water and whisk until thickened and reaches 170°F. Beat until cool and doubled in volume.
Whip the Cream: Beat heavy cream with powdered sugar until soft peaks form. Refrigerate.
Combine and Layer: Fold the whipped cream into the cooled custard mixture. Layer the mixture in the loaf pan, alternating with crumbled pralines and crushed espresso beans. Tap to remove air pockets.
Freeze: Fold the plastic wrap overhang over the top to cover. Freeze for at least 8 hours or overnight.