Prepare the Croissants: Begin by slicing the croissants in half horizontally. If they are too fresh, leave them out overnight or put them in a 300 degree oven for 10 to 15 minutes to dry out. Dry bread will absorb the custard mixture better.
Place the bottom half of the croissants on the bottom of a greased 12x7-inch baking pan overlapping when necessary to fill the entire bottom. Place the tops over the bottom layer.
Make the Custard: In a large mixing bowl, whisk together the heavy cream, brown sugar, liqueur, eggs, almond extract (or vanilla extract, and ground cinnamon until well combined.
Gently pour the custard mixture over the croissants. Some of the tops will be exposed and that's okay. Allow the croissants to absorb the liquid for 20-30 minutes.
Prepare the topping. First, cut the butter into the brown sugar and cinnamon with a pastry cutter or fork until you have a crumbling mixture. Toss in the pecans (and chocolate chips if you're adding them). Scatter the crumb and pecan mixture over the top of the croissants and into all the crevices. At this point, you can cover and refrigerate for up to 8 hours or overnight.
When you're ready to bake the bread pudding, set it out of the refrigerator while you preheat the oven to 350°F (175°C).
Bake for 40-45 minutes or until the pudding is set and the top is golden brown.
Allow the bread pudding to cool slightly before serving. You can serve it warm or at room temperature. It's perfect on its own or with a dollop of whipped cream or a scoop of vanilla ice cream.
Store leftover bread pudding in an airtight container in the fridge for up to 5 days. Reheat in the microwave or oven.
Notes
*You can omit the alcohol and substitute it with another 1/4 cup heavy cream.