Can I Make a Berakha on non-Kosher Food?

Rabbi Eliezer ben Ya’akov says: In the case of one who robbed another of a se’a of wheat, then ground it, kneaded it, and baked it, and he then separated challa from it, [i.e., he separated the portion of the dough that one is required to separate and then give to a priest,] how can he recite the blessing over the separation of challa? This individual is not reciting a blessing, but rather he is insulting/disrespecting God. And with regard to this it is stated: “The robber who recites a blessing disrespects Hashem (Psalms 10:3).”

Three who ate together as one are obligated to perform a zimmun [before bentching]... One who ate untithed produce [tevel], and first tithe from which its teruma was not separated… is not included among the three obligated with whom they ate in a zimmun.

Whoever eats forbidden food, wilfully or in error—recites no blessing either before or after. For example, if one eats of that which is Rabbinically regarded as Tevel (produce from which priest's dues and Levite's tithes should have been, but had not been separated), or eats Levite's tithes from which the priest's dues (two per cent by the original owners, and ten per cent by the Levite of his portion) had not been taken, or eats (outside Jerusalem) Second tithes (which should be consumed in Jerusalem), or consumes that which had been set apart for the Sanctuary and had not been properly redeemed, he does not recite the blessings for the food. Needless to add that no blessing is recited if flesh is eaten of a beast that was not properly slain or was pronounced unfit for consumption by Jews owing to a lesion, or if wine is drunk that is forbidden to Jews etc.

[The Rambam] made a big mistake [in understanding the mishna]. The mishna doesn’t say to not recite berachot, but it says that one does not do a zimmun for birkat ha-mazon because eating forbidden foods has no value in contributing to a zimmun, it’s like eating fruits [which is not satisfying enough to say birkat ha-mazon/zimmun after eating]. But why should you not make a beracha before and after eating [something forbidden], didn’t you benefit from eating it?!

If you ate something forbidden, even if it’s only rabbinically prohibited, you don’t participate in a zimmun and you don’t make a beracha on it before or after eating. If you ate something forbidden because your life was in danger, you should make a beracha before and after eating it.