May one bake Challahs for Shabbos at the same time he is baking meat or chicken?
If the meat or chicken is covered it is allowed to be done if the oven is clean of any meat or chicken residue. If the bread is covered it may be done in all cases. In such a case the Challahs remain Pareve. If they are both uncovered it is only permitted to do so if one will not eat the bread with dairy and is only baking enough to last that Shabbos, or is forming the Challahs in a special shape that reminds him of its meat status. If one transgressed and baked them together without fulfilling the above conditions then by today’s ovens that have a roofing, seemingly the bread is forbidden. One is to thus contact a Rav.]
May one bake Challahs directly after he baked meat or chicken in the oven? Do the Challahs remain Pareve in such a case?
If there is no residue of meat in the oven, then one may bake the Challahs in the oven even if it was previously used to bake meat. In such a case the Challahs remain Pareve. This applies even if the oven is Ben Yomo as Challahs are dry and hence does not release vapor. However some write one may never bake Pareve foods in a meat or milk oven which is Ben Yomo. If one did so they rule one may not eat the food together with milk but may eat it before or afterwards.
 See “A Semicha Aid for the Laws of Basar Bechalav” Chapter 97
 See Shach 108/11 or “A Semicha Aid for Learning the Laws of Taaruvos” chapter 108 Halacha 2I and 3A; Chochmas Adam 62/6; Kreisy 108/12; Kaf Hachaim 108/33; Igros Moshe 1/40; See Darkei Halacha p. 242; Mahrsham 3/208; Minchas Yitzchak 5/20; Kinyan Torah 1/24
Opinions that are lenient: See Peri Chadash 108/10 who argues on the entire ruling of the Shach ibid which prohibits the bread; See the following Poskim who are lenient in certain cases even if the bread was actually kneaded with milk or meat: ; Kreisy Upleisy 97/1 in name of his grandfather; Daas Eish 12 and Chamudei Daniel brought in Darkei Teshuvah 97/21Hakashrus 10 footnote 33 in name of Rav Moshe Halbershtam; Kreisy Upleisy 97/1 in name of his grandfather.
 See Igros Moshe 1/40; Pischeiy Halacha p. 27; 157; Hakashrus 1/40; Kinyan Torah 1/24; Minchas Yitzchak 5/20 or “A Semicha Aid for Learning the Laws of Taaruvos” chapter 108 Halacha 2I and 3A
 See Igros Moshe 1/40; Pischeiy Halacha p. 27; 157; Hakashrus 1/40
Some write that one is to simply turn the oven on for some time prior to baking the Pareve food and this will verify that any leftover food in the oven has become destroyed. [Kinyan Torah ibid]
 Igros Moshe 1/40
 See Pischeiy Halacha p. 27; 157; Hakashrus 1/40
 Hakashrus ibid