Preheat oven to 350F degrees and spray a baking sheet with a non-stick cooking spray. Set aside.
With electric mixer, cream 1&1/2 cups butter, granulated sugar and brown sugar together till creamy. Add the egg and vanilla, and beat till everything's incorporated.
In a small, heavy saucepan,on low heat, melt the 4 squares of chocolate. Remove from heat and slowly pour it into the butter mixture, with mixer on low speed.
Increase speed slightly and add the salt and flour, being careful not to overmix, or dough will get tough.
Reduce speed to low and add the coconut to the dough. Only mix long enough to incorporate everything together.
Shape the dough into a ball, a little larger than the size of a walnut and place them onto the prepared baking sheet. With your thumb, press a little well into the center of each cookie, so it will later hold the chocolate truffle filling.
Bake at 350 degrees for 10-12 minutes. Don't over bake. When done, cool on a rack.
While cookies are baking, prepare filling:
Truffle filling: In a medium saucepan, add the chocolate chips, cream and remaining 5 TBS. butter. Cook on low heat, just till the ingredients are melted together. Stir frequently. Remove from the heat.
Stir the desired flavored liqueur into the truffle filling, at this time, if you opt to use it.
Refrigerate the pan of warm truffle mixture for about 1&1/2 hours, or till it is the right consistency to pipe into the little well of each cookie. Stir the mixture a couple times, while it is chilling.
When truffle mixture is chilled enough, spoon it into a pastry bag or a zippered plastic bag with a small hole cut into one of it's corners, and pipe a nice sized dollop of chocolate truffle into the center of each cookie. (If you have a decorator tip, feel free to use it to pipe the truffle, but it's not necessary.)
These decadent cookies are best served at room temperature and can be stored at room temperature, not that there will be any left over to store! ENJOY!
Although the chilling time of the chocolate truffle is about 1&1/2 hours, it is worth the waiting time, as the cookies are very easy to make!