Cut the sliced brioche in half to make triangular wedges and line them up on a parchment-lined baking sheet. Bake until toasted but not too toasty, about 6 minutes.
Cut the pears in half. Scoop out the core and any tough surrounding flesh. Slice the pears to about 1/4 inch thick. Heat the butter in a non-stick skillet to medium-high heat. Mix in the olive oil. Place the pear slices in the pan, making sure not to crowd them. Sear until caramelized, about 3 minutes.
Spread a generous covering of brie on your brioche slices. Top with 1 to 2 pear slices, caramelized side up. At this point, you can opt to broil the assembled toasts just long enough to melt the brie or leave as is.
Drizzle the finished toasts with a few drops of lemon juice. Top with a couple flakes of Maldon and some freshly cracked black pepper.